How can I detect if a device token is obsolete?

How can I detect if a device token is obsolete?

References

Reference NO 1

http://stackoverflow.com/questions/15200972/how-can-i-detect-if-a-device-token-is-obsolete

Reference NO 2

http://stackoverflow.com/questions/11593767/gcm-multicastresult-which-result-is-from-which-device

Reference NO 3

http://grnscrn.com/bigblue.htm

Reference NO 4

http://en.wikipedia.org/wiki/Ethernet_hub

Reference NO 5

https://support.google.com/accounts/answer/1066447?hl=en

Reference NO 6

https://developer.mozilla.org/en-US/docs/Gecko_user_agent_string_reference

Reference NO 7

http://www.debian.org/doc/manuals/network-administrator/ch-tcpip.html

Reference NO 8

http://developer.apple.com/library/ios/documentation/uikit/reference/UIDevice_Class/