1.3 Flashcards
what is access point:
It’s the wireless network device inside the network.
Whats a MAC address:
It’s the Ethernet Media Access Control Address or the unique physical address of a network adapter.
How does the MAC address display?
it is 48 bits or 6 bytes and is shown in hexadecimal.
OUI stands for what?
Organizationally Unique Identifier.
MAC address 2 parts:
- OUI
2. Network Interface Controller-Specific
What is a Half-Duplex?
when a device cannot send and receive data at the same time, that device is half duplex.
What is Full-duplex
when a device can send and receive data at the same time, that device is Full-duplex.
what are some examples of half and full duplex devices:
all LAN hubs are half-duplex and switches are full-duplex unless its connected to other half-duplex devices.
How does a half-duplex device work?
It receives traffic on one interface and repeats it out to other interfaces.
T/F) in half-duplex devices, you can have two or more devices communicating at the same time.
False, if more than one device is communicating, we will have collisions.
Whats the other name for half-duplex:
CSMA/CD
(CS: Carrier Sense
MA: Multiple Access
CD: Collision Detect)
T/F) Half-duplex Ethernet is still being used to this day.
False. Not used any longer.
Explain how CSMA/CD work?
- First the device listens for an opening.
- Then it sends a frame of data (whenever it can, no queue)
- If a collision happens, then it will send a jam signal to let everyone know a collision happened, then it waits a random amount of time and resend the data.
What are CSMA/CA function characterization?
In this half-duplex, there is no collision detection since its not possible but it uses Collision Avoidance and RTS/CTS (ready to send, clear to send)
and it solves the hidden node problem.
What does a switch do?
- Forward or drop frames
- Gather a constantly updating list of MAC addresses.
- Maintain a loop-free environment using STP
Whats STP:
Spanning Tree Protocol
How does a switch learn the MACs?
A switch examines the incoming traffic. Then it adds the unknown MAC addresses to the MAC address table
Why does a switch floods an unknown MACs?
When a switch doesnt have the MAC address in the table or is in doubt, the switch sends the frame to everyone. this process is called flooding.
What does ARP stand for:
Address Resolution Protocol
What does an ARP do:
Determines a MAC address based in an IP address.
What do we use to view the local ARP table?
arp -a
T/F) Collision domain is difficult to be found these days.
True
How is a collision domain removed?
By adding a switch to a network and creating a full-duplex network.
What is a broadcast domain used for?
To send a message to everyone on the network.
how far would a broadcast go?
It pass by a bridge or a switch but it stops at the router.
What is a collision domain:
Is in a network of half-duplex devices when two or more devices try to communicate in that network at the same time.
What is a Unicast:
It’s a one on one communication and info exchange between 2 devices
what are some examples of unicast:
web surfing and file transferring
What is a broadcast:
When a device send info to everyone on a network at once.
What are some examples of broadcast:
Routing updates and APR requests
T/F) broadcasting is used in IPv6.
False. broadcasting can be used in IPv4 but not IPv6 and instead multicast is used.
What is multicast:
It is delivery of information from one device to specific interested devices.
What are some example of multicast:
Multimedia delivery and stock exchange
What is the issue with multicast?
It is very specialized and difficult to scale across large networks.
what does PDU stand for?
Protocol Data Unit
What is a PDU:
a unit of transmission (a different group of data at different OSI layers.
What are TCP and UDP PDU called?
TCP segment and UDP datagram.
What determines the size of the PDU?
MTU, Maximum Transmission Unit
What does MTU do?
Gives us the maximum IP packet to transmit.
What are the issues with fragmentation:
- Slows things down
2. It is difficult to know the MTU all the way through the path
How often do we configure MTU:
usually once based on the network infrastructure and they dont change often.
what do we use for troubleshooting the MTU:
by using ping
What is a LAN made of:
It’s a group of devices in the same broadcast domain.
What is a VLAN:
it’s the virtual local area network or a group of devices in the same broadcast domain separated logically instead of physically.
What is a VLAN trunk?
When two switches are connected using only one physical connection between switches but it is able to transmit multiple VLANs over that trunk.
What does ISL stand for?
Inter-switch Link
What is the standard for trunking?
It used to be ISL but now everyone uses the 802.1q standard.
how long are the VLAN IDs?
12 bits long and can have 4094 VLANs but 0 and 4094 are reserved VLAN numbers.