It is a network of users that share computer resources in a limited area.
LAN
Local Area Network
LAN
How are Local Area Networks defined?
In terms of protocol and the topology used for accessing the network.
A set of rules established for users to exchange information
Protocol
The network architecture used to interconnect the networking equipment.
Topology
What are the most common topologies for LANs?
Ring, Bus, and Star
Uses a token that is placed in the data channel and circulates around the ring.
Token Ring topology
A deterministic network
Token Ring Topology
Each station connected to the network ensures access for transmission of its messages at regular or fixed time intervals
Deterministic
What are the disadvantages of the Token Ring system?
- If an error changes the token pattern, it can cause the token to stop circulating.
What is a disadvantage of the Token Ring system from the troubleshooting and maintenance?
The token ring path must be temporarily broken or interrupted if a computer or any device on the network is to be removed or added to the network.
What is a solution to the troubleshooting and maintenance disadvantages of the Token Ring system?
Connect each computer or device on the network to a central token ring hub.
A device that manages the passing of the token instead of relying on individual computers to pass it.
Token ring hub
How does the token ring hub improve the network?
It improves the reliability of the network.
Topology whereas the computers share the media or coaxial cable for data transmission.
Bus topology
The coaxial cable that is looped through each networking device to transmit data in a bus topology
ThinNet
In this topology, all devices on the network can see each other’s data traffic.
Bus topology
Topology whereas each computer must wait for pauses in transmission or until the transmission from one device is complete before initiating a new transmission onto the network.
Bus topology
What are the disadvantages of a bus topology?
“1. Data can be corrupted if ore than one device on the network transmits at the same time and will have to be resubmitted.
- The use of the shared coaxial cable prevents data transmission from being very bandwidth-efficient.”
Which topology is seldomly used in modern networks?
Bus topology
What is the most common topology used in today’s LANs?
Star topology
Topology that uses twisted-pair cables with modular plugs to connect computers and other networking devices.
Star topology
Topology whereas each device is connected to a switch or hub
Star
A switch or hub facilitates the transfer of data between networking devices in this topology
star
Transmits data to all the devices connected in the star network
hub
Also called a multiport repeater
hub
Not meant for large networks, but are still used in some smaller, slower speed LANs
hub
A transmission from a hub in a star network to all the devices in the network connected to the hub
broadcast
Stores the hardware or physical address for each device connected to its ports in a star network
switch
Sends data transmissions directly to the port of the destination device on the network
switch
The physical input/output interfaces to the networking hardware
port
Where the cables physically connect to each other or a central switch or hub
Port
Only the intended destination device on this network will see the data traffic
star
What is an advantage of the star topology?
It improves the efficiency of the available bandwidth of the network
What is an advantage of the star topology from the troubleshooting and maintenance?
A device can be removed or added without disrupting other devices on the network
All devices are connected to each other
mesh topology
What is an advantage of the mesh network?
It provides full redundancy in the network data paths
What is a disadvantage of the mesh network?
The additional data paths increase the cabling cost and the network hardware cost. It is also very complex.
What type of applications is the mesh topology suited for?
high-reliability applications
What type of applications is the mesh topology not suited for?
general networking applications
Open systems interconnect reference model
OSI
Who was the OSI model developed by?
The International Organization for Standardization
What year was the OSI model developed?
1984
What is the purpose of the OSI model?
to enable different types of networks to be linked together
What is OSI meant for?
To provide a framework for networking devices that ensure compatibility in the network hardware and software.
What is the OSI model meant to accelerate?
The development of new networking technologies.
What is layer 1 of the OSI model?
Physical
The layer of the OSI model that provides the electrical and mechanical connection to the network.
physical
UTP, fiber, and network interface cards are examples of which layer of the OSI model?
physicaL
What is layer 2 of the OSI model?
Data link
Layer of the OSI model that handles error recovery, flow control (synchronization), and sequencing (which terminals are sending and which are receiving)
data link
Also called the media access control layer
data Link
The layer of the OSI model where the Media Access Control or MAC, addressing is defined
data lInk
Where is the Ethernet 802.3 standard defined?
In the MAC or media access control
Also called the Ethernet address
MAC or media access control
MAC addresses are an example of which layer of the OSI model?
data linK
What is layer 3 of the OSI model?
Network
layer of the OSI model that accepts outgoing messages and combines messages or segments into packets, adding a header that includes routing information.
network
Acts as the network controller
network layer of the OSI model
Internet Protocol (IP) and internetwork packet exchange (IPX) are examples of which layer of the OSI model?
networK
What is layer 4 of the OSI model?
Transport
layer of the OSI model that is concerned with message integrity between source and destination
transport
layer of the osi model that also segments/reassembles the packes and handles flow control
tRansport
Transmission control protocol (TCP) and User Datagram Protocol are examples of which layer of the OSI model?
transporT
What is layer 5 of the osi model?
Session
layer of the osi model that provides the control functions necessary to establish, manage, and terminate the connections as required to satisfy the user request
session
Network File system (NFS) and Structured Query Language (SQL) are examples of which osi model layer?
sessioN
What is layer 6 of the osi model?
Presentation
layer of the osi model that accepts and structures the messages for the application. If necessary, it will translate one code to another
presentation
layer of the osi model that is also responsible for data compression and encryption
pResentation
American Standard Code for Information Interchange (ASCII) and Joint Photographic Experts Group (JPEG) are examples of which layer of the OSI model?
presentatioN
What is layer 7 of the osi model?
Application
layer of the osi model that interacts with application programs that incorporate a communication component such as your internet browser and email
application
layer of the osi model that is also responsible for logging the message in, interpreting the request, and determining what information is needed to support the request
aPplication
Hypertext Transfer Protocol (HTTP) for web browsing, File Transfer Protocol (FTP) for transferring files, and Simple Mail Transfer Protocol (SMTP) for email transmission are examples of which osi model layer?
applicatioN
What is step one of the three basic steps in the process of isolating a network problem?
Is the connection to the machine down (layer 1)
What is step two of the three basic steps in the process of isolating a network problem?
Is the network down? layer 3
What is step three of the three basic steps in the process of isolating a network problem?
Is a service on a specific machine down? layer 7
A reply from” response from a ping indicates whate?”
A connection to the server is up
A request timed out” response from a ping indicates what?”
the network connection is down
What is the function of the data link layer of the osi model?
to provide for the flow of data MAC addresses
What is the function of the network layer?
to provide routing decisions IP, IPX
What is the function of the transport layer of the osi model?
to ensure error free packets
What is the function of the session layer of the osi model?
to establish, manage, and terminate NFS, SQL sessions
What is the function of the presentation layer of the osi model?
to ensure protocol conversion, data transactions ASCII, JPEG
What is function of the application layer of the osi model?
to support applications HTTP, FTP, and SMTP(email)
Which networking protocol is used in most modern computer networks?
Ethernet
A carrier sense multiple access with collision detection protocol for local area networks
Ethernet
Must have the capability to detect data collisions (collision detection) to avoid two or more computers from attempting to broadcast a message at the same time.
Ethernet systems
Provide grouping of information for transmission
packet
What does the header of a packet consist of?
The preamble, start frame delimiter, destination and source addresses, and length/type field
Preamble, start frame delimiter, destination mac address, source address, length/type, data, pad, and frame check sequence.
The structure of the Ethernet frame
An alternating pattern of 1s and 0s used for synchronization
The preamble of an Ethernet packet
A binary 8 bit sequence of 10101011 that indicates the start of the frame
The start frame delimiter of an Ethernet packet
The MAC address associated with the network adapter or Ethernet network interface card (NIC)
The destination and source MAC addresses of an Ethernet packet
An indication of the number of bytes in the data field if this value is less than 1500, or if the number is greater than 1500, and indication of the type of data format such as IP and IPX
The length/type of the Ethernet packet frame
The variable length of data being transferred from the source to the destiontion
The data of the Ethernet packet frame
A field used to bring the total number of bytes up to the minimum of 46 if the data field is less than 46 bytes
The pad of the Ethernet packet frame
A 4 byte CRC value used for error detection
The frame check sequence of the Ethernet packet frame
What is the minimum length of the Ethernet frame from destination MAC address through the frame check sequence?
64 bytes
a device that relays the wireless signals from an access point or wireless router into areas with a weak signal or no signal at all
range extender
Where can range extenders be used to improve connectivity?
Stores, warehouses, and public places using hotspots
a limited geopgraphic area that provides wireless access for the public
hot spot
What basic steps can help secure a wireless home network?
“1. Change the default factory password
- Change the default SSID
- Turn encryption on
- Turn off the SSID broadcast
- Enable MAC address filtering”
How should a default password on a wireless device be reset?
using a combination of alphanumeric characters
the name used to identify your network and is used by your access point or wireless router to establish an association
SSID
Service Set Identifier
SSID
How many characters can the SSID be?
32
What does the turning off the SSID broadcast of your access point or wireless router in your wireless home network do?
prevents the wireless system from broadcasting SSID
What happens when MAC addressing filtering is turned on?
only wireless devices that have specific MAC addresses will be allowed access to the network
What are ways of protecting your home network from outside threats?
“1.Network address translation
- Firewall protection
- establishing a VPN connection when transferring sensitive information”
What does a network address translation allow the outsider to see?
Only the router IP address
Why does the network address translation allow the outsider to only see the router IP address?
because the ip addresses of the internal networking devices are not provided on the Internet
Prevents unauthorized access to your network
a firewall
a type of firewall that inspects incoming data packets to make sure they correspond to an outgoing request
state packet inspection (SPI)
a virtual private network that establishes a secure network connection
VPN
type of connection that is encrypted
VPN connection
a technique that translates the private IP address of a computer to a public address for routing over the Internet
Network Address Translation (NAT)
a technique used by a router, where NAT translates the home’s network’s private IP addresses to the single public IP address assigned by the ISP
Overloading
What technique does a router use to track a port number for when a data packet is returned to a home network to idenfity which computer to deliver the packet to?
Port Address Translation (PAT)
a cable that has cross-connected TX/RX data lines
crossover
In a straight-through, how are transmit and receive signal pares aligned?
end to end
Also called an uplink port
Straight-through ports
allows the connection of a hub or switch to another hub or switch without having to use a crossover cable
an uplink port
Which devices require a cross-connect input port?
computers, printers, and routers
Which devices require a straight-through connection?
unlink connections to other switches or hubs
What does a link light on the switch or hub indcate?
that the transmit and receive pairs are properly aligned and the connected devices are comunicating
an Ethernet protocol used to verify that a communication link between two Ethernet devices has been established
link integrity test
Why are link pulses sent by each of the connected devices via the twisted pair cables?
to indicate that the link is up
when are link pulses sent when data is not being transmitted?
at regular intervals
Uses Internet Control Message Protocol (ICMP) echo request and replies to test that a device on the network is reachable
the ping command
Where is the ping command issued in Windows to verify the networking devices are communicationg?
the command window
twisted pair cables capable of carrying up to 1000 mbps (1 gigabit) of data up to a length of 100 meters
CAT6
What is the maximum length of the Ethernet fram from destination MAC address through the frame check sequence?
1518 bytes
Media Access Control
MAC
Each NIC or network interface card has a unique network address called what?
MAC address
What is the length of a MAC address?
6 bytes or 48 bits
A MAC address is displayed in which format?
12 hexadecimal digits
The Organizationally Unique Identifier (OUI) is which digits of the MAC address?
The first six digits
Indicates the vendor of the network interface
organizationally unique identifier OUI)
A unique value for each NIC assigned by the vendor
The last six digits of a MAC address
Also called the Ethernet address, the physical address, the hardware address, and the adapter address
MAC address
What does ipconfig/all display when entered as a command in the command mode or at the MS-DOS prompt?
MAC address
Which base are MAC addresses listed in?
hexadecimal (base-16)
Only provides the physical address for the network interface card
MAC address
A mac address does not provide what?
the network location, what LAN, or in which building, city, or country the network resides
Incorporates a unique address that identifies the computer’s network
Internet Protocol (IP)
Who assigns IP network numbers?
Internet Assigned Numbers Authority (IANA)
How many bits are in an IP address?
32
Identifies on which network the computer is located and differentiates the computer from all other devices on the same network
IP address
How many bit parts are each IP address divided into?
four 8 bit parts
What are class A ip addresses used for?
governments and very large networks
What is the maximum number of hosts for a class A ip address?
16,777 or 2^24
What are class B ip addresses used for?
midsize companies, universities
What are the maximum number of hosts on a class B ip address?
65,534 or 2^16
What are class C ip addresses used for?
small networks
What are the maximum number of hosts for a class C IP address?
254 or 2^8
What are class D ip addresses used for?
reserved for multicast groups
What do class A ip addresses begin with?
0 thru 127
What do class B ip addresses begin with?
128 thru 191
What do class C ip address begin with?
192 thru 223
what do class D ip addresses begin with?
224 thru 239
The first set of numbers in an IP address are what?
the network number
What does the network number do?
defines which network the IP packet is originating from or being delivered to
What are the last three sets of numbers in an IP address?
the Host number
The Host number is also called what?
the Host address
The portion of the IP address that defines the address of the networking device that is connected to the network
The Host number
What do the network number and the host number do when they are together?
display which network an IP packet is coming from or going to, and which device on that network an IP packet is coming from or going to.
Who assigns the host number?
the local network system administrator or your Internet Service Provider (ISP)
ipconfig in the command prompt will display what?
the IP address for your computer
IP addresses set aside for use in a private intranet
Private address
An internal Internetwork that provides file and resource sharing
intranet
Why can’t private addresses be used on the internet?
They are invalid addresses reserved for internal use and are not routable on the internet.
Can be used within a private LAN (intranet) to create an IP Internetwork
private addresses
uses IP addressing for indentifying devices connected to the network
IP Internetwork
Is also the addressing scheme used in TCP/IP networks
IP Internetwork
Transmission Control Protocol/Internet Protocol
TCP/IP
the protocol suite used for Internetworks such as the Internet
TCP/IP
Uses cables and connectors to establish the network connection
wired network
uses radio signals to establish the network connection
wireless network
What is the most common home network configuration?
wireless network
What are the advantages of a wired network?
“1. faster network data transfer speedds (within the LAN)
- relatively inexpensive to set up
- network is not susceptible to outside interference”
What are the disadvantages of a wired network?
“1. Cable connections typically require the use of specialized tools
- the cable installation can be labor intensive
- The cable installation can be expensive”
What are the advantages of a wireless network?
“1. mobility
2.simple installation
- no cables”
What are the disadvantages of a wireless network?
“1.security issues
2.data speeds within the LAN can be slower”
Another name for a wireless network and the abbreviated name for the WI-FI Alliance, or wireless fidelity
Wi-Fi
What is the Wi-Fi Alliance?
An organization whose function is to test and certify wireless equipment for compliance with the 802.11x standards
A group of wireless standards developed under IEEE 802.11
802.11x
What is the data transfer rate of 802.11a wireless standard?
54 mbps
What is the operating range for the 802.11a wireless standard?
up to 75 feet
802.11a standard operates at what GHz?
5 GHz
Which 802.11x wireless standards all operate at 2.4 GHz?
802.11b,g, and n
What are the data transfer rates and operating ranges for 802.11b wireless standard?
up to 11 mbps with ranges of 100-150 feet
What are the data transfer rates and operating ranges for 801.11g wireless standard?
up to 54 Mbps and up to 150 feet
The next generation of high speed wireless connectivity
802.11n wireless standard
What is the data transfer rate for 802.11n wireless standard?
4 x 802.11g speeds (200+ mbps)
What are the two most common broadband connections to the Internet Service Provider (ISP)?
via a cable modem and DSL
In some cases, what device may also have the configuration settings for managing the router, which can include the setting for connecting to the ISP?
One of the computers
A device used to interconnect wireless networking devices and to give access to wired devices, and establish the broadband internet connection to the ISP
wireless router
Is a hub or switch the best choice for interconnecting networking devices?
switch
A type of network adapter used in desktop computers
network interface card or NIC
Can be a NIC inserted into an expansion slot on the computers motherboard
A wired network adapter
Where does a PC Card adapter connect to?
Notebook computers
What does a PC card adapter do?
provides an RJ-45 jack for connecting to wired networks
The PC card adapter supports connects to which networks?
Both 10 mbps and 100 mbps networks
Which 802.11x wireless technologies are compatible?
b,g, and n
When there is a combination of wireless b, g, and/or n technologies, which frequency will be set for the combined technologies?
The slowest speed
Where does a wireless n adapter insert into?
A notebook or laptop computer PC card slot
Which wireless technologies offer the highest data transfer speed?
Wireless n
Where does a USB network adapter connect to?
The USB port on a computer
A networking device used to connect two or more networks using a single connection to your ISP such as your LAN and the Internet
A router
A device used to interconnect wireless devices and provide a connection to the wired LAN.
Access point
What does a wireless router contain?
A router, switch, and wireless access point
Which is the most common way to interconnect wireless LANs to the ISP’s access device?
A wireless router
A device used to provide high speed data access via your cable connection or via a telephone company’s DSL connection
broadband modem/gateway
combines a modem and a router into one network box
a gateway
a device that is used to make a broadband network connection from your home network to the ISP using your cable connection.
cable modem
What tool does a cable modem require at setup to separate the cable TV from the home network
a splitter
Who is the iSP for a cable modem usually?
the cable TV service provider
a device that is used to make a broadband connection from your home network to the ISP using the telephone line
DSL modem
Who is the ISP for a DSL modem?
the telephone company or separate ISP
What does a DSL connection to a DSL modem require?
The placement of filters on all telephone lines except the one going into the modem to prevent interference.
What issues should be considered when planning a home network?
data speed, cost, ease of implementation, appearance, home access, and public access
Which network offers the fastest speeds for a home network?
wired network
What data transfer rates can a wired network offer up to inside the home network?
up to 10 gbps
Which wireless technology can the best data transfer rates be achieved with in a wired home network?
wireless n technology
Which type of network is less expensive to implement in a home network?
wireless networks
Why does the wireless network offer the best appearance for a home network?
it has only one external connection to the ISP
Which network will offer the best data transfer speed for home access of the home network?
the wired network
the wireless network will offer what for home access of the home network?
best mobility
What is the limiting factor when considering the data transfer rate for public access?
the data rate transfer connection to and from the ISP
What are the four steps for troubleshooting wired and wireless home networks?
“1. Check the lights on the networking device
- Reboot the host computer connected to the router and reboot the router
- Verify the hardware cable or phone connection is in place
- Verify your network settings”
Wheat do incorrect lights on the networking device indicate?
a connection problem with your network device
Application Layer(7th layer)
Interacts with application programs that incorporate a communication component such as your internet browser and email (provides user interface)
Bus Topology
The computers share the media (coaxial cable) for data transmission
CAT6 (category 6)
Twisted-pair cables capable of carrying up to 1000Mbps (1 gigabit) of data up to a length of 100 meters
Crossover
Transmit and receive signal pairs are crossed to properly align the transmit signal on one device with the receive signal on the other device
CSMA/CD
Carrier sense multiple access with collision detection is the Ethernet LAN media-access method (used to prevent collisions in wired Ethernet networks) Used in wireless networks for to reduce collisions.
Data Link Layer (2nd layer)
Layer of the OSI reference model that handles error recovery.flow control (synchronization), and sequencing controls which terminals are sending and receiving. Media access is controlled (MAC) by the Data Link Layer
Deterministic
Access to the network is provided at fixed time intervals
Ethernet, Physical, Hardware, or Adapter Address
Other names for MAC address
Firewall Protection
Used to prevent unauthorized access to your network
Host Address/Number
The portion of the IP address that defines the location of the networking device connected to the network also called the hose address
Hotspots
A limited geographic area that provides wireless access for the public
Hub
Broadcasts the data it receives to all devices connected to its ports… it is possible for network devices to pick up a data intended for a different device… considered a multiport repeater. Is on the Physical Layer (layer 1)
IANA
The Internet Assigned Numbers Authority is the agency that assigns IP addresses to computer networks
ICMP
Internet Control Message Protocol (preform diagnostics, report errors, control the flow of data in the network)
IEEE
Institute of Electrical and Electronics Engineers, on of the major standard-setting bodies for technological development
Intranet
An internal network the provides file and resource sharing but it’s not accessed from the internet
IP Address
Unique 32-bit address the identifies on which network the computer is located as well as differentiate the computer from all other devices on the same network; they are logical addresses and can be found using the ipconfig/all command
IP Internetwork
A network that uses IP addressing for identifying devices connected to the network
ipconfig/all
Enables the MAC address information to be displayed from the command prompt
ISP
Internet service provider
Link Integrity Test
Protocol used to verify that a communication link between two Ethernet devices has been established.
Link Light
Indicates that the transmit and receive pairs are properly aligned
Link Pulses
Sent by each of the connected devices via the twisted-pair cables when data is not being transmitted to indicate that the link is still up
Local Area Network (LAN)
Network of users that share computer resources in a limited area
MAC Address
A unique 6-byte address assigned by the vendor of the network interface card; A MAC address has two portions. The OUI is comprised of the first 6 digits and the last half is assigned by the manufacturer.
Mbps
Megabits per second
Mesh Topology
All networking devices are directly connected to each other (fault tolerant; stations can still communicate if some segments go down)
Multiport Repeater
Another name for a hub
Network Address Translation (NAT)
Translates the private IP address to a public address for routing over the internet
Network Interface Card(NIC)
The electronic hardware used to interface the computer to the network
Network Layer (3rd layer)
Defines how data packets are routed in a network. Accepts outgoing messages and combines messages or segments into packets, adding a header that includes routing information (provides a logical path for data)
Network Number
The portion of the IP address that defines which network the IP packet is originating from or being delivered to
Organizationally Unique Identifier (OUI)
The first 3 bytes of the MAC address the identifies the manufacturer of the network hardware (ex. Network interface card has MAC address of 00-00-86-15-7A, the OUI is 00-00-86)
OSI
Open system interconnect
OSI Model
The seven layers describing network funcations
overloading
Where NAT translates the home network’s private IP addresses to a single public IP address
Packet
Provides grouping of the information for transmission
Physical Layer (1st layer)
Layer of the OSI reference model that provides the electrical and mechanical connection to the network Describes the media that interconnects networking devices
Ping
Command used to test that a device on the network is reachable (If you can’t connect to a networked computer, you can use the ping command to check connectivity) Used in windows in the command window
Port address Translation (PAT)
A port number is tracked with the client computer’s private address when translating to a public address
Ports
The physical input/output interfaces to the networking hardware
Presentation Layer (6th layer)
Layer of the OSI reference model that accepts and structures the messages for the application
Private Addresses
IP addresses set aside for use in private intranet
10.0.0.0 – 10.255.255.255
172.16.0.0 – 172.31.255.255
192.168.0.0 – 192.168.255.255
Protocol
Set of rules established for users to exchange information
Range Extender
Device that relays the wireless signals from an access point or wireless router into areas with a weak signal or no signal at all
RJ-45
The 8-pin modular connector used with CAT6/5e/5 cable
Service Set Identifier (SSID)
Name that is used to identify your wireless network and is used by your access point or wireless router to establish and association
Session Layer (5th Layer)
Layer of the OSI reference model that provides the control functions necessary to establish, manage, and terminate the connections (SQL and NFS technologies are on the session layer)
SSID
Service set identifier
Star Topology
The most common networking topology in today’s LANs where all networking devices connect to a central switch or hub, each device connects to a central point via a point-to-point link. Each device is connected to its own port
Stateful Packet Inspection (SPI)
Type of firewall that inspects
6to4 Prefix
a technique that enables IPv6 hosts to communicate over the IPv4 Internet
Access Control List (ACLs)
A basic form of firewall protection
ACK
Acknowledgement packet
AES
Advanced Encryption Standard
AH
Authentication Header
Anycast address
Is obtained from a list of addresses.
ARIN
American Registry for Internet Numbers
ARP
Address Resolution Protocol, used to map and IP address to its MAC address (the destination gets the sender’s addresses from the ARP request)
ARPAnet
Advanced Research Projects Agency network
Brute Force Attack
Attacker uses every possible combination of characters for the password
Buffer Overflow
Happens when a program tries to put more data into a buffer than it was configured to hold
CHAP
Challenge Handshake Authentication Protocol
CIDR
Classless interdomain routing
CIDR Block
The grouping of two or more class networks together; also called supernetting
Class A, B, C, D, and E
The five classes of IPv4
Classfull
the IP and subnet addresses are within the same network
Connection-Oriented Protocol
Establishes a network connection, manages the delivery of data, and terminates the connection
Denial of Service (DoS)
A service is being denied to a computer, network or server
DES, 3DES
Data Encryption Standard, Triple Data Encryption Standard
Dictionary Attack
Uses Known passwords and many variations (upper and lowercase and combinations) to try to log into your account
Diffie-Hellman
Key generation algorithm
Directed Broadcast
The broadcast is sent to a specific subnet
EAP
Extensible Authentication protocol
ESP
Encapsulating Security Protocol
Firewall
Used in computer networks for protecting the network; Personal firewall software is typically based on basic packet filtering inspections where the firewall accepts or denies incoming network traffic based on information contained in the packet’s TCP or IP headers.
Full IPv6 Address
All 32 hexadecimal positions contain a value other than 0 (double colons, 32, hex characters, 128 bits)
GRE
Generic Routing Encapsulation
Hex
Hexadecimal, base 16
ICANN
The Internet Corporation of Assigned Names and Numbers
IGMP
Internet Group Message Protocol (Used for streaming media… data is passed through to the application layer for immediate processing without error checking)
IKE
Internet Key Exchange
Internet Layer
Defines the protocols used for addressing and routing data packets
IP (Internet protocol)
Defines the addressing used to identify the source and destination addresses of data packets being delivered over an IP network
IP Tunnel
An IP packet encapsulated in another IP packet (a secure VPN connection between two endpoints in known as an IP Tunnel)
IPng
The next generation IP
IPsec
IP security is used to encrypt data between various networking devices (AES, ESP, and DES are security protocols, not TKIP which is wireless protocol)
IPv4
The IP version currently being used on the internet (Dotted decimal) Uses five classes of IP addresses, is being replaced by IPv6. Made up 4 bytes and octets. An Octet is 8 bits. 4 makes up 32 bits of an IP address.
IPv6
IP version 6 (unicast, multicast, and anycast all IPv6 addresses)
ISAKMP
Internet Security Association and Key Management Protocol
L2F
Layer 2 Forwarding
L2TP
Layer 2 Tunneling Protocol
Malware
Malicious programs
MD5
Message Digest 5
Multicast Address
Data packets sent to a multicast address are sent to the entire group of networking devices, such as group of routers running the same routing protocol
Multicasting
When one host sends data to many destination hosts
NCP
Network Control Protocol
Netstat -a -b
(a) Command used to display the ports currently open on a Windows operating system and (b) used to display the executable involved in creating the connection or listening port
Network Interface Layer
Defines how the host connects to the network
Non-Internet Rotatable IP Addresses
IP addresses no routed on the Internet
Packet Filtering
A limit is placed on the information that can enter the network
Packet Sniffing
A technique in which the contents of data packets are watched (assumes that the attacker can see the network data packets; performed using a machine attached to the network)
PAP
Password Authentication Protocol
PPP
Point-to-Point Protocol (the de facto standard in dial-up VPNs)
PPTP
Point to Point Tunneling Protocol
Prefix length notation
Another shorthand technique for writing the subnet mask except class boundaries are not being crossed
Proxy Server
Clients go through a proxy to communicate with secure systems
RIRs
Regional Internet registries, IANA-designated governing organizations responsible for IP address allocation by geographical location
SHA-1
Secure Hash Algorithm
Social Engineering
A way for an intruder to obtain enough information from people to gain access to the network
Spoof
Inserting a different IP address in place of an IP packet’s source address to make it appear that the packet came from another network
Statefull Firewall
Keeps track of data packet flow
Supernets
The grouping go two or mare class network together; also called CIDR blocks
Supernetting
Allows multiple networks to be specified by one subnet mask (allows the representation of multiple networks with one address)
syn
Synchronizing packet
SYN ACK
Synchronizing Acknowledgement packet
TCP
Transport Control Protocol (example of a connection oriented protocol)
Transport Layer Protocols
`Define the type of connection established between hoses and how acknowledgements are sent
UDP
User Datagram Protocol; UDP is a connectionless protocol that doesn’t use acknowledgements
Unicast Addresses
Used to identify a single network interface address, and data packets are sent directly to the computer with the specified IPv6 address
Virus
A piece of malicious computer code that, when opened, can damage your hardware, software, or other files
Well-known Ports
Ports reserved by ICANN
Worm
A type of virus that attacks computers, typically proliferates by itself, and can deny service to networks
10GBASE-T
10Gbps over twisted-pair copper cable (splits the data into 4 channels of 2.5G each) Uses multilevel encoding to reduce required bandwidth for tranmission
ACR
The attention-to-crosstalk ratio measurement compares the signal level from a transmitter at the far end to the crosstalk measured at the near end. A larger ACR indicates that the cable has a greater data capacity and also indicates the cable’s ability to handle a greater bandwidth. Essentially, it is a combined measurement of the quality of the cable. A higher ACR value (dB) is desirable.
Alien Crosstalk (AXT)
Unwanted signal coupling from one permanent link to another
Attenuation (Insertion Loss)
The amount of loss in the signal strength as it propagates down a wire or fiber strand (leakage and resistance cause attenuation in fiber optic systems)
Balanced mode
Neither wire in the wire pairs connects to the ground
Bottle-necking
Another term for networking congestion
Building Entrance
The point where the external cabling and wireless services interconnect with the internal building calbing
Campus Network
A collection of two or more interconnected LANs in a limited geographic area
CAT7/7a and CAT6a
UTP cable standards that support 10GB data rates for a length of 100 meters
Color map
The specification of which wire color connects to which pin on the connector
Cross-connect
A space where you are going to take one or multiple cables and connect them to one or more cables or equipment
Crossover Cable
Transmit and receive wire pairs are crossed (transmit and receive wires crossed, don’t connect to the same pins on each end)
Cross talk
Signal coupling in a cable
Delay Skew
This is a measure of the different in arrival time between the fastest and the slowest signal in the UTP wire pair
EIA
Electronic Industries Alliance
EIA/TIA 568-B
The standard that defines the six subsystems of a structured cabling system
ELTCTL
Equal Level Transverse Conversion Transfer Loss
EMI
Electromagnetic Interference
Entrance Facilities (EF)
A room set aside for complex electronic equipement
Equal Level FEXT (ELFEXT)
This measurement differs from NEXT in that the measurement is for the far end of the cable. Additionally, the ELFEXT measurement does not depend on the length of the cable. This is because ELFEXT is obtained by subtracting the attenuation value from the far-end crosstalk (FEXT!!) loss
Equipment Room (ER)/Backbone Cabling
Cabling that interconnects telecommunication closets in the same building and between buildings
F/UTP
Foil over twisted-pair cabling (better security, noise immunity for EMI) It minimizes signal leakage and provides noise immunity from EMI
FastEthernet
An Ethernet system operating as 100MBps
Full Channel
Consists of all the link elements from the wall plate to the hub or switch
Full Duplex
Computer system can transmit and receive at the same time (full duplex gigabit Ethernet uses 4 pairs)
Gigabit Ethernet / twisted pair cables
1000Mbps Ethernet; CAT6 and CAT5e rated for 1000Mbps
Horizontal Cabling
Cabling that extends out from the telecommunication closet into the LAN work area
Horizontal Cross-connect (HC)
The connection between the building distributors and the horizontal cabling to the work area or workstation outlet-another term used for the HC is the floor distributors (FD)
Hybrid Echo Cancellation Circuit
Removes the transmitted signal from the receive signal
IEEE 802.3an-200610GBASE-T
The standard for 10 Gbps
Intermediate Cross-connect (IC)
Also called the building distributor (BD), this is the building’s connection point to the campus backbone. The IC links the MC to the horizontal cross-connect (HC).
LCL
Longitudinal Conversion loss
Link
Point from one cable termination to another
Main Cross-connect (MC)
Usually connects two or more buildings and is typically the central telecommunications connection point for a campus or building. It is also called the main distribution frame (MDF) or main equipment room. The MC connects to Telco, an ISP, and so on. Another term for the MC is the campus distributor (CD).
Multilevel Encoding
Technique used to reduce in the required bandwidth required to transport the data
Near-end Crosstalk (NEXT)
A measure of the level of crosstalk or signal coupling within the cable, with a high NEXT (db) value being desirable
Network Congestion
A slowdown on network data traffic movement
Nominal Velocity of Propagation (NVP)
NVP is some percentage of the velocity of light and is dependent on the type of cable being tested. The typical delay value for CATD/De UTP cable is about 5.7 nsec per meter. The EIA/TIA specification allows for 548 nsec for the maximum 100-meter run for CAT5e, CAT6, CAT6, CAT6a, CAT7, and CAT7A
Power Sum NEXT (PSNEXT)
The enhanced twisted-pair cable must meet four-pair NEXT requirements, called PSNEXT testing. Basically, power sum testing measures the total crosstalk of all cable pairs. This test ensures that the cable can carry data traffic on all four pairs at the same time with minimal interference. A higher PSNEXT value is desirable because it indicates better cable performance.
Propagation Delay
This is a measure of the amount of time it takes for a signal to propagate from one end of the cable to the other. The delay of the signal is affected by the nominal velocity of propagation (NVP) of the cable.
PSAACRF
Power-sum Alien Attenuation Cross-talk Ratio Far-End
PSACR
Power sum ACR uses all four wire pairs to obtain the measure of the attenuation-crosstalk ratio. This is a measurement of the difference between PSNEXT and attenuation (insertion loss). The difference is measured in dB, and higher PSACR dB values indicate better cable performance.
PSANEXT
Power-Sum Alien Near-End Crosstalk
PSELFEXT
Power sum ELFEXT that uses all four wire pairs to obtain a combined ELFEXT performance measurement. This value is the difference between the test signal level and the cross-talk measured at the far end of the cable. A higher PSELFEXT value indicated better cable performance.
Return Loss
This measurement provides a measure of the ratio of power transmitted into a cable to the amount of power returned or reflected.
RX
Abbreviation for receive
STP
Shielded twisted pair; not good for noisy environments… blocks EMI, has metal foil placed around the wires
Straight-through
Transmit and receive signal pairs are aligned end-to-end
straight-through cable
The wire pairs in the cable connect to the same pin numbers on each end
TIA/EIA 568A
Wire color guidelines specified under the EIA/TIA568B standard (developed in 1995)
T568B
Wire color guidelines specified under the EIA/TIA568B standard
TCL
Transverse Conversion Loss
TCO
Telecommunications outlet
TCTL
Transverse Conversion Transfer Loss
Telecommunications Closet
The location of the cabling termination points that includes the mechanical terminations and the distribution frames (networking equipment, patch cables, backbone cabling, patch panels)
TIA
Telecommunications Industry Association
TR
Another name for the telecommunications closet
TX
Abbreviation for transmit
Wire-map
A graphical or text description of the wire connections from pin to pin
Work Area
The location of the computers and printers, patch cables, jackets, computers adapter cables, and fiber jumpers
Workstation or Work Area Outlet (WO)
Also called the TO (telecommunications outlet), it’s used to connect devices to the cable plant. The cable type typically used is CAT3, CAT5, CAT5e, CAT6, CAT6A, and various coaxial cables. Devices typically connected to these outlets are PCs, printers, servers, phones, televisions, and wireless access points.
Switch
Forwards a frame it receives directly out the port associated with its destination address (get the MAC address from the data packets) Minimize unneeded data traffic, isolate portions of the network
TCP/IP
Transmission Control Protocol/Internet Protocol, the protocol suite used for internet works such as the Internet
ThinNet
A type of coaxial cable used to connect LANs configured with a bus topology
Token Passing
A technique where an electrical token circulates around A network-control of the token enables the user to gain access to the network
Token Ring Hub
A hub that manages the passing of the token in a Token Ring network
Token Ring Topology / Network
A network topology configured in a logical ring that complements the token passing protocol (one failed station causes network shutdown, difficult to reconfigure, diffident to troubleshoot; each system must relay the token, if there is any failure the entire system goes down. It can be hard to determine which one it is.
Topology
Architecture of a network
Transport Layer (4th layer)
Layer of the OSI reference model that is concerned with message integrity between source and destination
Uplink Port
Allows the connection of a hub or switch to another hub or switch without having to use a crossover cable (an X label is on the uplink ports)
Virtual Private Network (VPN)
Establishes a secure network connection and is a way to protect your LAN’s data from being observed by outsiders
VPN
Virtual Private Network
Wired network
Uses cables and connectors to establish the network connection
Wireless network
Uses radio signals to establish the network connection wireless signal can be intercepted easier than wire signals
Wireless Router
Device used to interconnect wireless networking devices and to give access to wired devices and establish the broadband Internet connection to the ISP
Absorption
light interaction with the atomic structure of the fiber material; also involves the conversion of optical power to head
Chromatic Dispersion
The broadening of a pulse due to different propagation velocities of the spectral components of the light pulse (affects both single mode and multimode fibers)
Cladding
Material surrounding the core, which must have a lower index of refraction to keep the light in the core
dense wavelength division multiplexing (DWDM)
Incorporates the propagation of several wavelengths in the 1550-nm range for a single fiber
Dispersion
Broadening the light pulse as is propagates through a fiber strand (light isn’t a cause of dispersion, it is affected by dispersion)
Dispersion Compensating Fiber
Acts like an equalizer, canceling dispersion effects and yielding close to zero dispersion int he 1550-nm region (developed to increase the transmission capacity of older cabling; allows the use of 1550nm transmission on lines that were designed for 1310nm region)
Distributed Feedback (DFB) Laser
A more stable laser suitable for use in DWDM systems
DL
Diode Laser
Fiber Bragg Grating
A short strand of modified fiber that changes the index of refraction and minimized intersymbol interference
Fiber Cross-connect
Optical patch panel used to interconnect fiber cables
Fiber, Light Pipe, Glass
Terms used to describe a fiber-optic strand
FTTB
Fiber to business
FTTC
Fiber to the curb
FTTD
Fiber to the desktop
FTTH
Fiber to the home
Fusion splicing
A long-term method where two fibers are fused or welded together into one piece of glass
GBIC
Gigabit interface converter (optical-to-fiber interfaced used at 1 gigabit)
Graded-index Fiber
The index of refraction is gradually varied with a parabolic profile (overcomes modal dispersion)
IC
Interconnect fibers branch exchange-item D shows the jumpers connecting the main fiber cross-connect (item B) to the active equipment (item C)
IDC
Intermediate Distribution Closet
Index-matching Gel
A jelly like substance that has an index of refraction much closer to glass than to air
Infrared Light
Light extending from 680 nm up to the wavelengths of the microwaves
Isolator
An inline passive device that allows optical power to flow only in one direction
LED
Light-emitting diode
Logical Fiber Map
Shows how the fiber is interconnected and data is distributed throughout a campus (data distribution, fiber interconnections)
Long Haul
The transmission of data over hundreds or thousands of miles
Macrobending
Loss due to light breaking up and escaping into the cladding
Mechanical splices
Two fibers joined together with an air gap, thereby requiring an index-matching gel to provide a good splice
Microbending
Loss caused by verry small mechanical deflections and stress on the fiber
MM
Multimode
Modal Dispersion
The broadening of a pulse due to different path lengths taken through the fiber by different modes
Mode Field Diameter
The actual guided optical power distribution, which is typically a micron or so larger than the core diameter; single-mode fiber specifications typically list the mode field diameter
Multimode Fiber
A fiber that supports many optical waveguide modes; use light in the 850 nm and 1310 nm range
Numerical Apeture
A measure of a fiber’s ability to accept light
Optical Ethernet
Ethernet data running over a fiber link
Optical spectrum
Light frequencies from the infrared on up
Physical Fiber Map
Shows the routing of the fiber but also shows detail about the terrain, underground conduit, and entries into buildings
Polarization mode Dispersion
The broadening of a pulse due to the different propagation velocities of the X and Y polarization components of the light pulse
Pulse Dispersion
Stretching of received pulse width because of multiple paths taken by the light
Received Signal Level (RSL)
The input signal level to an optical receiver
Refractive Index
Ratio of the speed light in free space to its speed in a given material
SC, ST, FC, LC, MT-RJ
Typical fiber connectors on the market (need to be easy to install and economical)
Scattering
Caused by refractive index fluctuations; accounts for 96 percent of attenuation loss
Single-mode Fiber
Fiber cables with core diameters of about 7-10 um; light follows a single path (use light in the 1310 nm and 1550 nm range) Uses high-power, highly directional modulated light sources; single-mode fibers are used with lasers.
SM
Single mode
SONET/SDH
Synchronous optical network; protocol standard for optical transmission in long-haul communication/synchronous digital hierarchy
STS
Synchronous transport signals
Tunable Laser
Laser in which the fundamental wavelength can be shifted a few nanometers, ideal for traffic routing in DWDM systems
Vertical Cavity Surface Emitting Lasers (VCSELs)
Lasers with the simplicity of LEDs and the performance of lasers
XENPAK, XPAK, X2, XFP, SFP+
The ten gigabit interface adapter
Zero-dispersion Wavelength
Point where the dispersion is actually zero
Aging Time
The length of time a MAC address remains assigned to a port; length of time an IP address is assigned to a switchport
ARP Cache
Temporary storage of MAC addresses recently contacted
ARP Table
Another name for the ARP cache
Association
Indicates that the destination address is for an networking device connected to one of the ports on the bridge (describes a wireless connection and MAC address: wireless connection has been obtained, provides the client MAC address)
AUI Port
This is a 10Mbps Ethernet port. AUI stands for “attachment unit interface.”
Auto-negotiation
Protocol used by interconnected electronic devices to negotiate a link speed (failed negotiation can cause a link failure, not recommended for fixed data links) The link can only go as fast as the slowest link.
Auxiliary Input
Used to connect a dial-in modem into the router. The auxiliary port provides an alternative way to remotely log in to the router if the network is down. This port also uses an RJ-45 connection
Bridge
A networking device that uses the MAC address to forward data and interconnect two LANs (easy to install) Only forwards data to the specified port, isolated the network traffic, uses MAC addresses to forward data packets. The association tells the bridge where to forward a data packet. Works on the Data Link layer (layer 2)
Bridging Table
List of MAC addresses and port locations for hoses connected to the bridge ports
Broadcast
Transmission of data by a network device to all devices connected to its ports
Broadcast Domain
Any network broadcast sent over the network will be seen by all networking devices in this domain
Broadcast Storm
Excessive amounts of broadcasts; can cause network slowdown
Cisco Network Assistant (CNA)
A management software tool from Cisco that simplifies switch configuration and troubleshooting
Console Input
Provides a RS-232 serial communications link into the router for initial router configuration. A special cable, called a console cable, is used to connect the console input to the serial port on a computer. The console cable uses RJ-45 plugs on each end and requires the use of an RJ-45 to DB9 adapter for connecting to the COM1 or COM2 serial port
Content Addressable Memory (CAM)
A table of MAC addresses and port mapping used by the switch to identify connected networking devices
cut-through switching
The data packet is forwarded to the destination as soon as the destination MAC address has been read; cut thought switching doesn’t read the entire frame, just the MAC address. Low latency
Dynamic Assignment / Addressing
MAC addresses are assigned to a port when a host is connected (addresses are assigned dynamically when using dynamic addressing)
Enterprise Network
Term used to describe the network used by a large company
Error Threshold
The point where the number of error in the data packets has reached a threshold and the switch changes from the cut-through to the store-and-forward mode
Fast Link Pulse (FLP)
Carries the configuration information between each end of a data link (designed to operate over limited bandwidth)
FastEthernet Port (FA0/0, FA0/1, FA0/2,…)
Naming of the FastEthernet ports on the router
Flooding
The term used to describe what happens when a switch doesn’t have the destination MAC address stored in CAM
Gateway
Describes the networking device that enables hosts in a LAN to connect to networks (and hosts) outside the LAN
Half-Duplex
The communications device can transmit or receive but not at the same time
Isolating the Collision Domains
Breaking the network into segments where a segment is a portion of the network where the data traffic from one part of the network is isolated from the other networking devices
Layer 2 Switch
An improved network technology that provides a direct data connection for network devices in a LAN
Logical Address
Describes the IP address location of the network and the address location of the host in the network
Managed Switch
Allows the network administrator to monitor, configure, and manage select network features (managed switches can be managed remotely)
Media Converter
Used to adapt a layer 1 (physical layer) technology to another layer 1 technology
Multicast
Messages are sent to a specific group of hosts on the network
Multilayer Switch (MLS)
Operates at layer 2 but functions at the higher layers
Multiport Bridge
Another name for a layer 2 switch
Network Address
Another name for the layer 3 address (routers use the network address to route packets)
Network Slowdown
Degraded network performance
Power On/Off
Turns on/off electrical power to the router
Router Interface
The physical connection where the router connects to the network; serial, Ethernet, and auxiliary can all be used to connect to the network.
Routing Table
Keeps track of the routes to use for forwarding data to its destination
Secure Address
The switch port will automatically disable itself if a device with a different MAC address connects to the port
Serial Ports
Provides a serial data communication link into and out of the router, using V.35 serial interface cables
Store-and-Forward
The entire frame of data is received before any decision is made regarding forwarding the data packet to its destination
Switch Latency
The length of time a data packet takes from the time it enters a switch until it exits.
Translation Bridge
Used to interconnect two LANs that are operating two different networking protocols
Transparent Bridge
Interconnects two LANs running the same type of protocol
Wire Speed Routing
Data packets are processed as quickly as they arrive
Access Point
A transceiver used to interconnect a wireless and a wired LAN (looks as the SSID to determine if the data packet is intended for it’s network)
Ad Hoc
Another term used to describe an independent network
Backscatter
Refers to the reflection of the radio waves striking the RFID tag and reflecting back to the transmitter source.
Basic Service Set (BSS)
Term used to describe an independent network
Beacon
Used to verify the integrity of a wireless link
BWA
Broadband wirless access
CSMA/CA
Carrier sense multiple access/collision avoidance
DSSS
Direct Sequence Spread Spectrum
Extended Service Set (ESS)
The use of multiple access points to extend user mobility. (allows a wider range of wireless signals using roaming)
FHSS
Frequency Hopping Spread Spectrum
Hand-off
When the user’s computer establishes an association with another access point
Hopping Sequence
The order of frequency changes
Inquiry Procedure
Used by Bluetooth to discover other Bluetooth devices or to allow itself to be discovered
ISM
Industrial, scientific, and medical
Last Mile
The last part of the connection from the telecommunications provider to the customer
MIMO
A space-division multiplexing technique where the data stream is split into multiple parts called spatial streams (uses space-division multiplexing to transmit different data streams in parallel)
NLOS
Non-line-of-sight
OFDM
Orthogonal Frequency Division Multiplexing
Paging Procedure
Used to establish and synchronize a connection between two Bluetooth devices
Pairing
When a Bluetooth device is set up to connect to another Bluetooth device
Passkey
Used in Bluetooth Security to limit outsider access to the pairing
Piconet
An ad hoc network of up to eight Bluetooth devices
Pseudorandom
The number sequence appears random but actually repeats
Radio Frequency Identification (RFID)
A technique that uses radio waves to track and identify people, animals, objects, and shipments (full speed tollbooths, tracking shipments, border crossing) Parameters that define an RFID system is frequency of operation, power, and protocol
RADIUS
Remote Authentication Dial-In User Service (prevents unauthorized users to connect to the network as well as preventing users from connecting to rogue access points)
Roaming
The term used to describe a user’s ability to maintain network connectivity as he moves through the workplace
Site Survey
Performed to determine the best location(s) for placing the access point(s) to provide maximum RF coverage for the wireless clients (conducted both inside and outside)
Slotted Aloha
A wireless network communications protocol technique similar to the Ethernet protocol
Transceiver
A transmit/receive unit
U-NII
Unlicensed National Information Infrastructure
Wi-Fi
Wi-Fi Alliance(md) and organization that tests and certifies wireless equipment for compliance with the 802.11x standards
WiMAX
A broadband wireless system based on the IEEE 802.16e standard (30 mile max range)
WLAN
Wireless Local Area Network
WPA
Wi-Fi Protected Access
The Transport Layer (4th layer)
The transport layer protocols in TCP/IP are very important in establishing a network connection, managing the delivery of data between a source and destination host, and terminating the data connection (TCP and UDP are the only protocols on the Transport layer).
HTTP Port number
80
Bluetooth
Operates in the 2.4 GHz band; 802.11n, 802.11b, 802.11g (802.11a operated in the 5GHz range)
Core size of multimode cables
62.5
Patch Cable
Used to make the physical connection to the wall palate
Stretching of a received pulse is due to
Pulse-dispersion and Multiple Paths taken by the light waves
EIA/TIA568-b.2 and 568-2.1
Specify the cabling components and transmission of copper cabling hardware
10.10.20.250
Example of a private IP address, a nonreturnable Internet IP address, Class A address
Antivirus software
Signatures or definitions contain traits of the specific virus or worm
MAC address filtering
Only devices with specified layer 2 addresses will be allowed to access the network… lets you specify which devices can connect to the network
10101010
Decimal equivalent of 170
Wireless Access Point
Provide MAC functions to allow users to connect to each other; provides 802.11 MAC layer functions
Cisco LEAP
User must provide the correct passwod
Router Routing tables
Keep track of the addresses needed to route data. Contains addresses of adjacent routers and the networks that they can reach. It also includes the metric and method of learning the route. Use the ip route command to the the routing table.
Maximum length for multimode fiber optic cable
2000 meter or 2 km
wired networks
can have data rates as high as 100Gbps
no ip directed-broadcast network command
Prevents networks from becoming intermediate sites for network attacks. On a Cisco router prevents a network form becoming an intermediate site for a network attack
Hexadecimal equivalent of 1011
B = 1011 = 11
Serial Interface
Used to create a T1 connection; sometimes has a built-in CSU/DSU
802.11 technologies
Don’t use visible light; use FHSS, DSSS, infrared
Secure a wireless home network
Turn on encryption; turning on WEP, WPA or WPA-2 will encrypt the data
Class c usable IP network addresses
192.0.0.0 – 223.255.255.255 (there are 24 network bits; the first three octets are used with 24 bits total)
150.25.191.255
broadcast address for 150.25.151.68 with a mask of 255.255.192.0
How many wire pairs are used for gigabit Ethernet
4: all 4 wire pairs are used for transmission at 1 Gbps speeds
Wireless security guidelines
Use firewalls, turn on access point security features. Technology in any frequency band may be used and 3rd party tools must be used end-to-end.
Network Segment
A segment is associated with each networking device; the networking link between 2 LANs
Intrusion detection
the monitoring of data packets passing through the network to catch potential attacks; the monitoring of data packets passing through the network to catch ongoing attacks. The first issue of intrusion is Social Engineering.
Private IP address
Cannot be used on the Internet, only Intranets
OC-3 bit rate
155.52 Mbps
UTP wire pair length difference
can be due to poor manufacturing, can be due to inconsistent twists, cause the cable not to be certified… cable testing will reveal these issues. The inconsistent length can cause failure if one wire is over 100 meters while the others are not. Due to the difference in the cable twists for each wire pair.
255.255.255.224
Expressed as a /27 using CIDR notation because there are 27 1s in the subnet mask
192.168.55.0 dived into multiple subnets, need at lest 30 host ID’s in each subnet; maximum number of subnets you could have?
8: Class C address and we must use 5 bits for our hoses (2 to the 5th -2 = 30 hosts). That leaves 3 bits to use for subnets. 2 to the 3rd = 8 subnets
Probing
Indicators of repeated attempts to make connections to certain machines
Core
Carries the light signals in a fiber optic cable
Static Assignment
MAC address that has been manually assigned
SMTP Port Number
25
Router
Interconnect LANs; routers know where to send packets coming into or leaving the LAN; router ports commonly refereed to as interfaces which provide the physical connection to the network. Operates at the Network Layer (layer 3)
Ethernet (DIX) frame after the Preamble
Destination address, Source address, Type/Length, Data, Pad, FCS
Fiber optic communication system
Source, cable, connectors, photodiode… the link may have splices but it must have connectors
255.255.255.252.0
Expressed as /22 using CIDR notion because there are 22 1s in the subnet mask
well-known ports
ICANN reserves these ports for particular protocols
SYN Flood
Attackers send SYN packets to set up virtual connections that use up the connection buffer… denial-of-service attack characterized by using all connections available on a computer
How many usable host IP addresses are provided: network IP address of 192.168.12.0 and a subnet mask of 255.255.255.252
2
Telnet Port
23
DSL Modem
Used to connect to a broadband network through your telephone connection only. Broadband modems can connect using cable or telephone technology.
Physical Architecture of a computer network
Topologies, A physical topology is the actual layout of the network.
SLA ID
Used to identify subnets in an IPv6 address
802.11u
802.11x standard increases security by incorporating user authentication, not 802.11u
Correct order sequence of packets that are sent to set up a virtual TCP connection
The three-way handshake is used to create virtual TCP connections: SYN, SYN-ACK, ACK
802.11g advantage
Compatible with 802.11b, high speed
What tools are needed to make a UTP cable?
Crimping Tool and strippers are used to terminate UTP cables
FTP Port Number
21
Layered Protocol Specifications
Multi vendor interoperability, easier to develop, easier to learn; Multivendor engineering not a benefit because doesn’t specify how it should work, just what it needs to be able to do.
Designing a LAN
- document all devices 2. develop and addressing scheme, physically connect devices and configure devices to communicate
With an address of 197.15.22.31 and a subnet mask of 255.255.255.224 how many bits have been borrowed to create a subnet?
- 224 = 11100000, 3 bits on
Light detector characteristics
Responsivity, response speed, spectral response
Decimal equivalent of 11110000
240