Invalid timer
'the length of time that must expire (90 sec) before a router determines that a route has become invalid,it will come to this conclusion if it hasn't heared any updates about a particular route for that period. ' Sybex
holddown timer
'the number of seconds a route is supressed while waiting for a new update to be reveived .If a new update is not received before the holddown timer expires, the flush timer will start.When the flush timer expires, the route is removed from the router'
Sybex
But when you type show ip protocol
routing protocol is 'rip'
sending updates every 30 seconds, next due in 6 seconds INVALID AFTER 180 SECONDS, HOLDDOWN 180 , flushed after 240
Sybex