Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am using CORE to develop some network emulations to teach some network concepts. One of those concepts is the correct setup of

  1. a recursive DNS server for local clients;
  2. an authoritative DNS server for a domain; and
  3. the reverse delegation for IPv4 and IPv6 prefixes.

Considering the documentation nature of the emulation, I have being using TEST-NET, TEST-NET2 and TEST-NET3 prefixes described in RFC5737. I also found out about RFC6303, which was written by a member of ISC (bind's developers), which states:

The following zones correspond to those address ranges from [RFC5735] and [RFC5737] that are not expected to appear as source or destination addresses on the public Internet; as such, there are no globally unique names associated with the addresses in these ranges.

Is there any way to configure bind9 to act as a recursive DNS server that bypasses the behavior established on RFC6303 (i.e., make recursion beginning with the root server, even if it belongs to one of the TEST-NETs address range)?

share|improve this question
up vote 0 down vote accepted

Check the BIND 9 Administrator's Reference Manual for your version. You want to look into the commands to enable/disable empty-zones.

  • "enable-empty-zones" allows you to turn them all on or off
  • "disable-empty-zones" allows you to disable specified ones individually

The default setting for empty zones (enabled or not) depends on what series of BIND you are running; it changed relatively recently (I can't recall for certain but I think in 9.7 or 9.8.)

I am assuming that you are interested in using this within your classroom simulated environment or in an isolated network where you plan to operate your own DNS root. Please use this responsibly -- don't deluge the real-world root servers with requests for RFC 1918 zones, etc.

share|improve this answer
Yes, the configuration would be used in a classroom simulated environment. Thank you very much for your explanation: using "disable-empty-zones" option for each TEST-NET solved this issue. – AYHarano Mar 12 '13 at 20:10

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.