in order to be able to swtich dns records / clients real-time we need to have the resolver to work at the fact of connection to server.
this will allow to use the following:
if we want redundancy we just add several DNS records for RR
if we want to distribute users (load balance) we add user records to certain servers only, other servers will issue a connection deny until correct server is reached
actually this is required for redundancy too as we do not want users to attach to different servers at once
in order to be able to swtich dns records / clients real-time we need to have the resolver to work at the fact of connection to server.
this will allow to use the following: