Hi Rene ,
I have few doubts for type4 LSA as per below statement
" This makes R1 an ASBR (Autonomous System Border Router). What happens is that R1 will flip a bit in the router LSA to identify itself as an ASBR. When R2 who is an ABR receives this router LSA it will create a type 4 summary ASBR LSA and flood it into area 0."
On Router LSA of ASBR , The E bit will be flipped , the ABR will receive it and generate type 4 . How this thing will work in NSSA . Does the ASBR in NSSA will do the same and NSSA ABR will generate type4 and also convert type7 to type5 ?