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3.28 Returning a Default Record

3.28.1 Problem

You want a name server to return the same record regardless of the domain name looked up.

3.28.2 Solution

Occasionally, administrators want to set up a name server that maps every domain name to the same IP address. To do that, configure the name server as a root name server, add an A record to the wildcard domain name in the root zone and omit any delegation. For example, the root zone might look like this:

$TTL 86400
.    IN    SOA    default-ns.corp.example. hostmaster.corp.example.    (
     2002042600 1h 15m 30d 1h )
     IN    NS    default-ns.corp.example.

default-ns.corp.example.    IN    A

*.    IN    A

3.28.3 Discussion

Most administrators probably take one look at this configuration and think, "Why in the world would I ever need a name server like that?" But for some applications, this kind of name server can come in handy. Think of those in-room, high-speed Internet access services that hotels offer: after you connect and get an IP address via DHCP, you reach the service's web site regardless of the URL you type in. This kind of name server could make up part of that solution.

One minor thing to note: BIND 8 and BIND 9 name servers treat wildcard domain names differently. On a BIND 9 name server, the wildcard in the zone above would match all domain names except default-ns.corp.example and domain names that end in that string. On a BIND 8 name server, the wildcard wouldn't match domain names that end in example. You'd need to add another A record to a different wildcard domain name to match those domain names:

*.example.    IN    A

3.28.4 See Also

Section 3.27 for instructions on setting up a root name server, and "Internal Roots" in Chapter 11 and "Wildcards" in Chapter 16 of DNS and BIND.

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