Troubleshooting clarity question.

In the given example fa0/11 on switch1 connects to router1 on fa0/1. Fa0/1 is on swith1 connected to PC1.



Switch 1:
[code:1]
SW1# show interfaces fa0/11
FastEthernet0/11 is down, line protocol is down (notconnect)[/code:1]

[code:1]
SW1#show interfaces status
Port Name Status Vlan Duplex Speed Type
Fa0/1 disabled 1 auto auto 10/100BaseTX
[/code:1]
Router 1:
[code:1]R1#show interfaces fa0/0
FastEthernet0/0 is administratively down, line protocol is down[/code:1]

[code:1]
R1#show ip int bri
Interface IP-Address OK? METHOD Status Protocol
FastEthernet0/0 172.21.100.1 YES NVRAM administratively down down
FastEthernet0/1 unassigned YES NVRAM administratively down down
Serial0/0/0 unassigned YES NVRAM administratively down down
Serial0/0/1 unassigned YES NVRAM administratively down down
[/code:1]



I know the show commands are a significant tool for troubleshooting so I wanted to ask what are all the different status types and protocol types on a router and on a switch? Also in what situations would you see the various combination types?

[code:1]FastEthernet0/11 is down, line protocol is down (notconnect)[/code:1]

FastEthernet0/11 is down = layer 1
line protocol is down = layer 2[/code]

That is a good start and I thank you. But I already understand what the codes mean (because it's pretty self explanatory) I was more or less wondering when you could expect to see such problems and what are the different "TYPES" of responses. I found an example for LAN below but I'm still looking for WAN.

All the ones in your table are applicable to WAN except port security. Status of Up/Down on a serial interface can be seen when encapsulations are different on each end.

There is also a status of standby mode when configuring backup interfaces.

[code:1]FastEthernet3 is standby mode, line protocol is down[/code:1]

I haven't read anything about a standby mode yet I'm guessing it's basically for a redundant port that isn't activated until an admin activates it or a line fails?