Some various questions from the last time I took the CCNA

[maturus]

What does the IP Subnet Zero command do, does it enable the use of say 0-7 in a 248 mask?

What does it mean when the Line is up but the line protocol is down?

There was a drag and drop question about osi layer 1 and 2, does anyone have any suggestions for this question (I know I can't remember everything on the left column so this might just be dumb of me to be asking for general comparisons.)

There was a question about what Show CDP Neighbors is used for, I know what I use it for, but that wasn't an option, what is the most official answer?

 

[Jsteve]

Subnet-Zero allows you to use 0-any subnet. This command is on by default. Otherwise you would start your subnet range at 1.

Line up protocol down - indicates that you are receiving good L1 connection (line up), but you are not receiving data link layer (protocol down). this could be due to the remote router being down or the telco circuit is bad.

CDP is a cisco L2 protocol that allows you to see other cisco device information that are directly connected.