How does a child find its parent?

Spain, Dr. Jeffry A. spainj at
Tue May 8 18:10:36 UTC 2012

> Reading the section on delegation in the O'Reilly book, I'm confused about
> something: The parent is configured to delegate the subdomain to the child
> with glue records, etc. But how does the child know who to ask if a host in the
> subdomain requests a record in the parent zone? They don't show any
> configuration example for that other than making the child a slave for the parent zone.

I think the confusion relates to the separate roles of authoritative name servers and recursive resolvers. A host in the subdomain would ask a recursive resolver to find a record in the parent domain, or for that manner any record, and the resolver would find it through the standard recursive resolution process starting from the DNS root. The slave server, which is not a recursive resolver but an authoritative server, would not be a party to that. If the slave needed to contact the parent for any reason, it would also use a recursive resolver to find the parent's address. That recursive resolver would be configured in /etc/resolv.conf or in Windows as a DNS entry in the network interface configuration.

Jeffry A. Spain
Network Administrator
Cincinnati Country Day School

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