Day 2 - CSMA / CD, Switching, and VLANs Flashcards
What is CSMA/CD?
Carrier Sense Multiple Access with Collision Detection
What does Carrier Sense mean?
That the wire is listened to in order to determine whether there is a signal passing along it.
What does Multiple Access mean?
More than one device is using the cables on the segment.
What is Collision Detection?
An algorithm used by a protocol to determine whether frames on the wire have become damaged due to hitting another frame.
Do switches reduce or increase the amount of collision domains?
Switches increase the number of collision domains.
If four PCs are connected to a switch how many collision domains are there?
Four.
Do switches or routers separate Broadcast domains?
Routers.
Do hubs reduce or increase the amount of collision domains?
Neither. Hubs extend the collision domain they are a part of.
What are the commands to adjust the speed on an interface?
interface [interface name]
speed [10,100,auto]
Do switches switch packets, frames or segments?
Frames.
What type of frame is switched out of all interfaces but the one on which they were received?
Broadcast and frames without a known destination (not in the MAC table).
What are the three main actions a switch must perform to function?
Forwarding or filtering (dropping) frames based on destination MAC addresses
Learning MAC addresses from incoming frames
Using STP to prevent Layer 2 loops
Any delay in passing traffic is know as ?
latency.
What are the three ways Cisco switches can switch traffic and which way is the default on modern switches?
Cut-through
Store-and-forward (default)
Fragment-free
What are the pros and cons of Cut-through switching?
Fastest switching method/lowest latency
No error checking
What are the pros and cons of Store-and-forward switching?
Error checking via CRC
Highest latency
What are the pros and cons of Fragment-free switching?
Quick and reliable
Only checks the first 64 bytes of a frame so any errors after that will be forwarded
What is CRC error checking?
Cyclic Redundancy Check
What is the minimum size of an Ethernet frame?
64 bytes
Fragment-free switching is also know as ?
runt-free switching
Hubs are also know as ?
multiport repeaters
Do hubs store MAC addresses?
no
The memory chip contained in a switch is know as a ?
application specific integrated circuit (ASIC)
Where is the switch table listing devices and ports stored?
Content Addressable Memory (CAM)
What is the switch command to display the CAM table?
show mac-address-table
What does OUI stand for?
Organizationally Unique Identifier
A MAC address is made up of how many bits and are they hex or binary?
48 binary bits
A MAC address is made up of a OUI of 24 binary bits and a ? of ? bits?
Vendor’s Number
24 binary bits
Name the seven components of the IEEE 802.3 Ethernet frame
Preamble Start-of-frame delimiter (SFD) Destination address Source address Length Data Frame-check sequence
What is the Preamble in an Ethernet frame?
synchronises and alerts the network card for the incoming data
What is the SFD in an Ethernet frame?
Start-of-frame delimiter, it indicates the start of the frame
What are the three different types of Destination MAC addresses?
Unicast
Broadcast
Multicast