Hello Sathish
Yes, you’re on the right track. The reason the LSAs learned through the virtual link are still in the LSDB even after removing the virtual link is due to the DNA flag. When an LSA has the DNA flag set, it prevents the LSA from aging out of the LSDB, meaning the LSA stays indefinitely until explicitly removed or until the OSPF process is removed, or the device is reset.
This behavior occurs because OSPF’s DNA flag is typically set for LSAs that originate from interfaces marked as point-to-point or virtual links to ensure they persist as long as possible across the network.
Now depending on the vendor and the implementation, simply clearing the OSPF process doesn’t always clear out LSAs marked with DNA. Clearing the OSPF process typically initiates a soft reset rather than a full teardown of the OSPF database. When you clear the process, OSPF re-establishes neighbor relationships, refreshes LSAs, and recalculates the routing tables, but it doesn’t entirely flush LSAs marked with the DNA flag out of the LSDB.
To remove them completely, a reload or a removal of the OSPF config is necessary.
I hope this has been helpful!
Laz