General Questions Part 1 Flashcards
(99 cards)
FCS
Frame Check Sequence (FCS) is an error-detecting code added to a frame in a communications protocol to determine if the frame arrived intact.
Preamble
The preamble functions like the outriders in a presidential motorcade. They tell everyone ahead to wake up and pay attention: something important is coming. Apart from being a “get ready” notification, the preamble also serves as a clock synchronization device.
Full Duplex
Send and receive data simultaneously
Half Duplex
Cannot send and receive data simultaneously
CSMA/CD
Short for carrier sense multiple access/collision detection. Before a node transmits data, it checks or listens to the network. When the network is not busy, the node sends its data. If it detects traffic, it will wait a random amount of time and try again. Collision Detection (CD) will happen if two or more nodes send data down the wire and they collide, the nodes will be notified and wait a random amount of time and try again. No longer an issue on modern networks, happened on older Ethernet networks with hubs.
Carrier Sense
Can detect what is going on over the transmission medium.
Multiple Access
Every node on the network has equal rights to access and use the shared medium, but they must take turns.
Collision Detection
If two or more nodes send data down the wire and they collide, the nodes will be notified and wait a random amount of time and try again.
Broadcast Domain
A broadcast domain is a logical division of a computer network in which all nodes can reach each other by broadcast at the data link layer. A broadcast domain can be within the same LAN segment or it can be bridged to other LAN segments. Separated by routers.
Collision Domain
A collision domain is a network segment connected by a shared medium or through repeaters where simultaneous data transmissions collide with one another. Separated by switch/bridge.
Unicast
One-to-one relationship, one station sending information to another single station.
Broadcast
One-to-many relationship, send from one station to all stations on a broadcast domain.
Multicast
One-to-many relationship, send from one station to all interested stations.
LAN
Local Area Network - A group of devices in the same broadcast domain
VLAN
Virtual Local Area Network - A group of devices in the same broadcast domain, separated logically rather than physically.
VLAN ID
Virtual Local Area Network Identification - 12 bits long, 4,094 VLANS.
Trunking
Trunking is a technique used in data communications transmission systems to provide many users with access to a network by sharing multiple lines or frequencies. As the name implies, the system is like a tree with one trunk and many branches. Trunking is commonly used in very-high-frequency (VHF) radio and telecommunication systems.
Trunking can also be defined as a network that handles multiple signals simultaneously. The data transmitted through trunking can be audio, video, controlling signals or images.
Loop Protection
IEEE standard 802.1D to prevent loops in bridged (switched) networks. Without loop protection, two switches connected to each other will send traffic back and forth forever.
IEEE standard 802.1D
Prevents loops in switched networks, used practically everywhere.
What are the STP port states?
Blocking - Not forwarding to prevent a loop
Listening - Not forwarding and cleaning the MAC table
Learning - Not forwarding and adding to the MAC table
Forwarding - Data passes through and is fully operational
Disabled - Administrator has turned off the port
RSTP
Rapid Spanning Tree Protocol (IEEE 802.1w). Latest upgrade to STP, convergence from 30 to 50 seconds to 6 seconds. Backwards compatible with 802.1D STP.
Routing Table
Data table stored in a router that lists the routes to a particular network destination.
Static Routing
Add routes to a router manually, done by an admin.
Dynamic Routing
Routes in a router are added automatically.