*Cisco in its documentation says:*

**After a default of 30 minutes the router that originated the entry resends the LSA, with a higher sequence number, in a link-state update (LSU), to verify that the link is still active.**
**If the LSA were to reach its maximum age (max age) of 60 minutes, it would be discarded**

*in OSPF: Anatomy of an Internet Routing Protocol - Page 160*

**When an LSA reaches the age of MaxAge (60 minutes), it is removed from consideration by the OSPF routing calculation. ..**

*In CCNP Authorized Self-Study Guide: Implementing Cisco IP Routing (ROUTE)* 

**in one paragraph it says the same thing as 60 minute and somewhere else it points 4 LSDB refresh timer which equals to 120 minutes is the max age timer**

*In for Dummies it says:*  [For Dummies][1]

**Because a router expects to receive updates every 30 minutes, you may be wondering what happens if an update does not show up on schedule. If an update is not received within four intervals (120 minutes), the router is aged out of the topology database. This might happen if something unexpected happens to the router, such as a power supply failure or becoming unplugged.**

**so which one is true???** 60 minutes or 120 minutes??


  [1]: http://www.dummies.com/how-to/content/working-with-open-shortest-path-first-ospf-routing.html