The Domain Name Service (DNS) is a worldwide, distributet directory for the translation of domain names into IP addresses and vice versa. For example the domain name dns1.uni-tuebingen.de resolves to the IP address 22.214.171.124.
The resolution takes place when using Internet services through the appropriate application programs (e.g. browsers) by request to the dedicated name servers.
To ensure that all computers connected to the network can have the same time, the ZDV offers a time service that is synchronized with the offical reference time.
With the help of ntp (network time protocol) computers can be set to an exact time. Moreover, the protocol offers further possibilities, e.g. to adjust the clock more precisely with the help of several timeservers or to synchronize several computers to a common time.
The time is imported on two routers with the help of separate computers with connected "atomic clocks" and compared to each other. The distributed time therefore has an accuracy of "stratum 2". If one connection to the source computer is lost, the accuracy can drop to "stratum 3".