Here is an example on how to show dirmngr's internal table of OpenPGP keyserver addresses. The output is intended for debugging purposes and not part of a defined API.
gpg-connect-agent --dirmngr 'keyserver --hosttable' /bye
To inhibit the use of a particular host you have noticed in one of the keyserver pools, you may use
gpg-connect-agent --dirmngr 'keyserver --dead pgpkeys.bnd.de' /bye
The description of the
keyserver command can be printed using
gpg-connect-agent --dirmngr 'help keyserver' /bye