ns5.uibk.ac.at has one IP number , but the reverse is ns5.univie.ac.at. ns5.univie.ac.at point to the same IP. uibk.ac.at is a domain controlled by three nameservers. Two of them are on the same IP network. Incoming mail for uibk.ac.at is handled by two mailservers at uibk.ac.at themselves. They are on the same IP network. uibk.ac.at has one IP number. ns5.uibk.ac.at is hosted on a server in Austria.