Hey Rene,
First off, I just wanted to say that I really love the pin feature that pins the diagrams to the lower right side of the monitor. It has made studying so much more convenient on your site!
Anyway, I just wanted to point something out on this lesson. In the passage below:
“When we look at R3 you’ll see network 192.168.12.0 /24 as inter-area (LSA Type 3) and 1.1.1.0 /24 as external type 2 (LSA Type 5). First we’ll create a loopback interface on R3 and redistribute it into OSPF to show you the NSSA area.”
I think it should read:
“When we look at R3 you’ll see network 192.168.12.0 /24 and a default route as inter-area (LSA Type 3)”.
Since area 1 has been configured as a stub area, we won’t see 1.1.1.0 /24 as external type 2 (LSA Type 5).