Allows you to filter routes from the routing table. For CCNA purposes, this is usually done through access lists.
Router(config-router)#distribute-list <list> <in/out>
Router(config-router)#distribute-list <list> <in/out> <interface>
|<in/out>||Whether the router is receiving or sending the route|
In this example, we will apply a distribute-list to R2. First, we will see what OSPP routes we have on R2.
R2(config)#do show ip route ospf
Next, we will set an access-list to only allow 18.104.22.168 and use it in a distribute-list.
R2(config)#access-list 25 permit 22.214.171.124
Finally, we see only 126.96.36.199 is in the routing table.
R2(config-router)#do show ip route ospf