DNS on Windows 2000, Second Edition

A More Restricted Name Server

You may want to restrict your name servers even further—stopping them from even trying to contact an off-site server if their forwarder is down or doesn’t respond. You can do this by telling the server not to fall back to using the recursive resolution process if no forwarders respond: check the Do not use recursion box on the Forwarders configuration tab (see Figure 10-9). The terminology is confusing: this checkbox has nothing to do with the kind of query being sent to the forwarders. As we said earlier, a name server that’s forwarding always sends a recursive query to its forwarders. What this checkbox determines is what happens after that recursive query is sent, which we discuss next. The BIND name server configuration syntax calls this kind of forwarding name server a forward-only server, which we think is a good name.

A forward-only server is a variation on a server that forwards. It still answers queries from its authoritative data and cache data. However, it relies completely on its forwarders; it doesn’t try to contact other servers for information if the forwarders don’t give it an answer.

The slave server contacts each forwarder only once, and it waits a short time for the forwarder to respond. Listing the forwarders multiple times directs the forward-only server to retransmit queries to the forwarders and increases the overall length of time the forward-only name server will wait for an answer from forwarders. You might want to consider ...