hello Nihar
By default, LDP advertises its LSR ID as the transport address within the LDP discovery hello messages. This can also be seen in the Wireshark capture shown in the lesson where the LSR ID is the same as the transport IP:
However, if you choose to you can change the transport IP to use a different address using the discovery transport-address command. More about this command can be found here:
I hope this has been helpful!
Laz