DNS service records and DNS alias entries in UCS

dns
ucs3
service
records

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Problem:

What are the DNS service records and DNS alias entries used for in UCS?

Solution:

Some central settings are managed via the domain name service (DNS) in UCS domains. DNS service records can be used to specify computers which offer certain services within the environment. DNS alias entries are used to access services via a fully qualified domain name (FQDN).

Different entries (records) are used in the domain name service to identify computers within a DNS domain which offer certain services. The MX record (mail exchange) of a domain contains the computer name of the mail server, for example. In addition to entries for special services such as in the case of the MX record, there are also general service records which can be used for services of your choice.

A DNS service record contains the name of the service and the transport protocol as components of the name. One or multiple FQDNs are listed in a service record. The port via which the service can be reached, the weighting and the priority are listed in each computer name. When multiple computer names are used, the weighting and priority can be used to influence in which order they are contacted.

A DNS service record can be viewed via the command host:

# host -t SRV _domaincontroller_master._tcp.firma.de
_domaincontroller_master._tcp.firma.de has SRV record 0 0 0 master1.firma.de.

The following DNS service records are used in an UCS domain:

* _domaincontroller_master._tcp - hostname of UCS domaincontroller master
* _kerberos._tcp - each kerberos server of the UCS domain that is reachable via TCP
* _kerberos._udp - each kerberos server of the UCS domain that is reachable via UDP
* _kerberos-adm._tcp - the administrative kerberos server
* _ldap._tcp - each UCS domaincontroller
* _pkgdb._tcp - UCS system on which the package database is used

The following DNS alias entries are used as standard:

* univention-directory-manager - Current UCS domaincontroller master

* univention-repository - repository server of the UCS domain