Some useful commands to identify the Cisco hardware components and their respective Serial Numbers on different platforms.
Sh version :
The most common use of this command is to determine which version of the Cisco IOS a device is running.
this command also offers different usesful information like the IOS version, ROM bootstrap, uptime, RAM quantity, FLASH capacity and many more. Coming back to our topic from this post.
You can see below an excerpt of the show version command on C6500 platform:

1. To check hardware serial number:
Case1 : On 3560 series devices
sh ver | in Motherboard serial|SFP Module serial|Power supply serial|System serial|Top Assembly
Case2 : 6500 series devices
sh ver | in Motherboard serial|SFP Module serial|Power supply serial|System serial|Top Assembly
incase this command not providing any response please go one by one.
2. To check Power supply serial no on 6500 series device:
Sh inventory
3. How to check system, motherboard, Chassis serial number on 6500 series devices:
show idprom backplane | in Serial

4. To check serial number of different module.
show idprom module 1 | in Ser
show idprom module 2 | in Ser , …….
Or we can run this command,
sh module version

Case3 : To check system serial number:
sh version
sh inventory | in SN
Case4 : To check hardware serial number on ASR devices:
Sh version to check motherboard serial number
sh inventory | in SN to check power serial number
show diag chassis eeprom to check PCB serial number
sh inventory to check subslots

Case5 : To check hardware serial on Nexus
Sh inventory To check module, chassis, power-AC

To check up to 20 Cisco devices, enter a comma-delimited or space-delimited list of serial numbers in the field provided, and click the Check button. To check more than 20 Cisco devices, complete these steps to use the Bulk input method. Every system administrator should know how to breakdown a device serial number. This could be very useful when you operate many Cisco devices. SN explanation is pretty easy, please find the rules below. Cisco serial numbers always have the same format: LOCYYWWXXXX, there LOC = Location code (Factory code) YY = Manufactured Year code (See.

Case6: to check serial number on Router 3945
sh diag
sh diag | in PCB
sh diag | in Chassis

1. Well it depends on what type of Cisco devices you are trying to pull the Serial Numbers for. For say 2960/3750 series switches you can use the OID: 1.3.6.1.4.1.9.5.1.2.19. If if is an ASA you can use the OID: 1.3.6.1.2.1.47.1.1.1.1.11. What other devices do you need this for? Here is the link to Cisco's MIB browser tool.
2. How can i check someones Cisco ID to verify that he is Certified or not. I can verify it by his Cisco Certification ID Number but how can i check it by Cisco ID which is started by CSCO123456789 or its Registration number 123456789 (Not Certificate Verification ID).

Case7: to check on ACE load balancer
sh hardware
Case8: to check on router 1900 series
sh diag
Case9: to check on Wireless access point
sh ver | in Serial

Cisco Serial Number

Cisco Serial Number Search

Cisco Serial Number Lookup Tool