In case that the connection to any of the internal routers/networks are not available I want the core router not to use the default route to look for any of the internal networks.

Configure a null0 route in your IGP core which covers all the IGP address space, then redistribute into area 0.

Example:

  ip address 10.0.0.0 255.0.0.0 null0

Now redistribute into ospf... You can optionally add a high admin distance if your routing policy requires it.

In case that the connection to any of the internal routers/networks are not available I want the core router not to use the default route to look for any of the internal networks.

Configure a null0 route in your IGP core which covers all the IGP address space, then redistribute into area 0.

Example:

  ip route 10.0.0.0 255.0.0.0 null0

Now redistribute into ospf... You can optionally add a high admin distance if your routing policy requires it.

Example:

  router ospf 100
      redistribute static subnets

In case that the connection to any of the internal routers/networks are not available I want the core router not to use the default route to look for any of the internal networks.

Configure a null0 router in your core which covers all the IGP space, then redistribute into area 0.

Example:

  ip address 10.0.0.0 255.0.0.0 null0

Now redistribute into ospf... You can optionally add a high admin distance if your routing policy requires it.

In case that the connection to any of the internal routers/networks are not available I want the core router not to use the default route to look for any of the internal networks.

Configure a null0 route in your IGP core which covers all the IGP address space, then redistribute into area 0.

Example:

  ip address 10.0.0.0 255.0.0.0 null0

Now redistribute into ospf... You can optionally add a high admin distance if your routing policy requires it.