A More Restricted Forwarding 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 for this domain box on the Forwarders configuration tab (see Figure 11-9). 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.
However, you must ask yourself if it ever makes sense to use a forward-only server. Such a server is completely dependent on the forwarders. You can achieve much the same configuration (and dependence) by not running a forward-only server at all; instead, configure your hosts’ resolvers to point to the forwarders you were using. ...
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