Delegating a Subdomain

When your domain reaches a certain size, or you decide to distribute the management of parts of your domain to various entities within your organization, you can divide the domain into subdomains. Within your own domain, you can delegate any number and level of subdomains to distribute control and management responsibility. You need not register these subdomains with the parent network. The organization that owns a zone or subdomain is responsible for maintaining the data and ensuring that up-to-date data is available from multiple, redundant servers.

You can create a subdomain without delegating it by specifying resource records that refer to the subdomain within the parent’s zone.

For example, div.inc.com contains a host that stores the complete database of employee records, called emp. To put emp in the personnel.div.inc.com domain, add the following records to the db.div.inc.com domain.

emp.personnel   IN    A      192.253.253.10
                 IN    MX      emp.personnel.div.inc.com

To delegate a subdomain, complete the following steps:

Set up the name servers for the subdomain.
Edit the existing zone file, db.domain on the name server for the parent domain, as follows:
- Add an NS resource record for each name server of the new subdomain.
- Add A records to specify the Internet addresses of the name servers listed in the NS records.
After modifying the domain data files, issue the following command to restart the name server for the parent domain:
/usr/sbin/sig_named restart
This causes named to reload its databases.

Example of Delegating a Subdomain

Consider the domain nmt.edu. and the subdomain plt.nmt.edu. The hosts venus.nmt.plt.edu and moon.plt.nmt.edu are the name servers for the plt.nmt.edu. subdomain. After you set up the name servers for the subdomain plt.nmt.edu, add the following entries in the db.nmt.edu. file to delegate the plt.nmt.edu. subdomain to the new plt.nmt.edu. name servers on venus and moon:

plt.nmt.edu         86400  IN   NS       venus.plt.nmt.edu.
                    86400  IN   NS       moon.plt.nmt.edu.
venus.plt.nmt.edu.  86400  IN   A        123.4.5.678
moon.plt.nmt.edu.     86400  IN   A         67.8.9.10

Delegating a Subdomain

Technical documentation

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Example of Delegating a Subdomain