Interesting Networking Interview Questions

1) How can you make sure the remote interface(NIC) is up if the firewall is blocking your icmp requests and you have no other access to the system.

2) What is the difference between Network Address translation and Packet Forwarding?

3) Is it possible to implement anyone out of congestion control or reliable data transfer algorithms in UDP protocol?

4) Can I say in wireless, presentation and sessions layer are in between data link layer and network layer?

5) Is there a protocol at the Physical Layer in Ethernet Based networks? How do ethernet devices with different speed and technology communicate?
OR
A link means device + transmission medium.
How is link failure detected?

6) Question about watchdog_timeo (net_device member variable) & tran_start?