Federating DNS

Any fully qualified DNS name can be used in the global context. When a DNS name is encountered in the global namespace, it is resolved using the resolver library. The resolver library is the DNS name-resolution mechanism. A DNS name typically resolves to an Internet host address or to DNS domain records. When the global context detects a DNS name, the name is passed to the DNS resolver for resolution. The result is converted into an XFN reference structure and returned to the requester.

The contents of DNS domains can be listed. However, the listing operations might be limited by practical considerations such as connectivity and security on the Internet. For example, listing the global root of the DNS domain is generally not supported by the root DNS servers. Most entities below the root, however, do support the list operation.

DNS hosts and domains are distinguished from each other by the presence or absence of name service (NS) resource records associated with DNS resource names.

• DNS domain names. If an NS record exists for a resource name, then that name is considered to be the name of a domain, and the returned reference is of type inet_domain.

• DNS host names. If no NS record exists for a resource name, then that name is considered to be the name of a host, and the returned reference is of type inet_host.

DNS can be used to federate other naming systems by functioning as a non-terminal naming system.

For example, an enterprise naming system can be bound to doc.com in DNS such that the FNS name .../doc.com/ refers to the root of that enterprise's FNS namespace.

The enterprise naming system is bound to a DNS domain by adding the appropriate text (TXT) records to the DNS map for that domain. When the FNS name for that domain includes a trailing slash (/), the TXT resource records are used to construct a reference to the enterprise naming system.

For general information about DNS, see the in.named man page or the DNS chapters in Solaris Naming Setup and Configuration Guide.