When you were a CCNA candidate, you mainly knew show version as the command that told you what a router's configuration register was. Obviously, there's a lot more information than that! Here's show version on one of my switches:

SW1#show version
Cisco Internetwork Operating System Software
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(19)EA1c, RELEASE SOFTWARE
(fc2)
Copyright (c) 1986-2004 by cisco Systems, Inc.
Compiled Mon 02-Feb-04 23:29 by yenanh
Image text-base: 0x80010000, data-base: 0x8058A000

ROM: Bootstrap program is C2950 boot loader

SW1 uptime is 11 hours, 42 minutes
System returned to ROM by power-on
System image file is "flash:/c2950-i6q4l2-mz.121-19.EA1c.bin"

cisco WS-C2950-12 (RC32300) processor (revision P0) with 20808K bytes of memory.
Processor board ID FOC0814X3G9
Last reset from system-reset
Running Standard Image
12 FastEthernet/IEEE 802.3 interface(s)

32K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address: 00:0F:90:E1:C2:C0
Motherboard assembly number: 73-5782-13
Power supply part number: 34-0965-01
Motherboard serial number: FOC08150PHU
Power supply serial number: DAB08145W2B
Model revision number: P0
Motherboard revision number: A0
Model number: WS-C2950-12
System serial number: FOC0814X3G9
Configuration register is 0xF

A lot of good stuff here! Highlighted from the top down:

The IOS version
The device uptime (really good for settling "hey, did anyone restart this switch today?" arguments)
Image filename
Amount and type of memory
Standard or Enhanced Image
Motherboard and power supply serial numbers
MAC addresses
Model number
... and the configuration register setting!
Another handy and often-overlooked switch troubleshooting tool is show cdp neighbor detail. You know what the basic output of show cdp neighbor looks like:

show cdp neighbor details gives you a great deal more information. Let's look at the output of this command for the neighbor SW2 only:

SW1#show cdp neighbor detail
-------------------------
Device ID: SW2
Entry address(es):
Platform: cisco WS-C2950-12, Capabilities: Switch IGMP
Interface: FastEthernet0/12, Port ID (outgoing port): FastEthernet0/12
Holdtime : 126 sec

Version :
Cisco Internetwork Operating System Software
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(19)EA1c, RELEASE SOFTWARE
(fc2)
Copyright (c) 1986-2004 by cisco Systems, Inc.
Compiled Mon 02-Feb-04 23:29 by yenanh

advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=0000000
0FFFFFFFF010221FF000000000000000F90E22540FF0000
VTP Management Domain: ''
Native VLAN: 1
Duplex: full
Management address(es):

Again, some great troubleshooting information here. Highlighted from the top down:

- The neighbor's hardware platform and capabilities
- The ports on the remote and local devices that are directly connected
- The neighbor's IOS version
- The CDP version ("advertisement version")
- The neighbor's native VLAN
Run these command regularly in your home Cisco lab and know where to find every piece of information listed here - you just never know when you might need to do that for real!

To your success,

Chris Bryant

CCIE #12933