@yogijain Hi,
type 6 LSA is used in the enhanced OSPF named MOSPF, MOSPF send the data packets from a single source address to the multi destination address, or a group of members which monitor the D class address.
If you want to learn more detailed information about MOSPF, you can search the MOSPF and check the RFC 1585, which is the official documentation for MOSPF