Step 5: Delegate the domain names to be managed by ADNR to the selected name servers from the parent domain's name server
Typically, the DNS domains that ADNR manages are subdomains of an existing DNS domain. For resolvers to reliably find resource records in the ADNR-managed subdomains, the ADNR-managed subdomain must be delegated by its parent domain. This enables resolvers to find resource records in the ADNR-managed subdomain if those resolvers are not pointing directly to the ADNR-managed name server. DNS queries from resolvers can follow the DNS delegation tree downward from the root domain, if necessary, and find an authoritative name server for the ADNR-managed subdomain.
Delegating a subdomain from a parent involves updating the parent domain's zone data file. In the parent's zone data file, an NS record and an associated A or AAAA glue record is added to represent each authoritative name server for the child domain. For example, to delegate the ADNR-managed mvsplex.mycorp.com zone from the mycorp.com zone, the following resource records are added to the zone data file for the mycorp.com zone:
mvsplex 86400 IN NS mvsnameserver.mvsplex.mycorp.com.
86400 IN NS networknameserver.mvsplex.mycorp.com.
mvsnameserver.mvsplex.mycorp.com. 86400 IN A 10.5.1.1
networknameserver.mvsplex.mycorp.com. 86400 IN AAAA 2001:0DB8:0:0:8:800:200C:417A
The example resource records delegate the mvsplex.mycorp.com zone to two authoritative name servers, one of which must be the master name server and the other a secondary name server.