- On condition that the particular config was saved by Prime (earlier) and that the switch was entered with a correct snmp write community (string), and is snmp-reachable (via that string), from Prime.
http://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/infrastructure/3-0/user/guide/pi_ug/chgdevconfig.html#pgfId-1053377
This also implies that the switch was previously known to Prime, and has configuration archives from it.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '