In scenario below, the GSLB service on BLR and BLRGV showed effective state Down
As per KB: https://support.citrix.com/article/CTX214755
Effective state was down as MEP was down, and hence it was not able to identify health of vServer.
With further troubleshooting it was identified, that MEP does not comes UP, as BLR site was sending TCP RST to BLRGV site.
On further decoding, it was found, the MEP validation failed because of incorrect credentials.