Hello Mohanad
There are a few things to consider when filtering routes. There’s a difference between filtering LSAs, and filtering routes. Filtering LSAs will block the actual transmission of the LSAs, which means the prefixes they contain will not be found in the OSPF database. However, this can only take place at an ABR, and LSAs can be filtered only between areas. Alternatively, you can prevent specific prefixes from entering the routing table by using distribute lists. The prefixes remain in the OSPF database, and are advertised, but are not placed in the routing table of the specific router.
If you want to filter external routes (Type 5 LSAs) from one area to another, use LSA Type 5 filtering, more about which you can learn at the following lesson:
If you simply want to prevent a particular prefix from entering the routing table, you can use distribute lists as described below:
I hope this has been helpful!
Laz