Unit 3 - Essential Networking

Question 1

Which layers do the Linux network support and what us the responsibility of each?

Answer 1

• Linux networking extensively supports Layer 2 and Layer 3
• Layer 2 is the Data Link Layer and is responsible for correct local delivery of packets between nodes.
• Layer 3 is the Network Layer and is responsible for moving data packets between networks.

Question 2

Why is SSH considered more secure then Telnet?

Answer 2

SSH is encrypted where as Telnet is not.

Question 3

What is the highest priority network in Linux?

Answer 3

Local host (127.0.0.1)

Question 4

What does every basic network need?

Answer 4

• IP address for host
• Gateway address
• Broadcast address
• Netmask for network

Question 5

What are the differences between multicast, unicast and broadcast?

Answer 5

• Broadcast is to all machines
• Unicast is to one machine
• Multicast is to group of machines

Question 6

How to see all stats for network interfaces?

Answer 6

ip -s link

Question 7

In 'ip -s link' what do the following show?
–Errors 
–Dropped
–Overruns
–Frame
–Carrier
–Collisions

Answer 7

–Errors –CRC Error in packet

–Dropped –Kernel buffers overflowed

–Overruns –Card buffer overflowed

–Frame –Frame length not a multiple of 8 bits

–Carrier –Probably a fault in the card

–Collisions –tx collided with another frame

Question 8

Given a desktop Linux machine with an IP of 10.0.1.14/24, and a gateway which is 1 less than the broadcast address, write down the ip commands needed to define the interface and routing table.

Answer 8

ip addr add 10.0.1.14/24 broadcast 10.0.1.255 dev eth1
ip route append 10.0.1.0/24 dev eth1
ip route append default 10.0.2.254