I am trying to understand the reverse dns implementation of bind. in my lab setup, i have a pxe server witn dns configured. it has 21.168.192.in-arpa.arpa reverse lookup zone file. i am using foreman to deploy remote machine. ip of my foreman server is i create any host in foreman, it creates reverse lookup entry in db file. if i try to assign ip to my client other than 21 in third octat ex-, foreman shows error with reverse dns. My understanding on this is that foreman is not able to find the db file 22.168.192.in-arpa.arpa and showing error. Is my configuration is wrong. should i create db file with network id or do i have to create separate file for each range.


Bind is the service responsible for reverse lookup, so that's where you have to go looking first.

You mention, but that actually covers and since you say you have a 21.168.192.in-arpa.arpa it sounds like bind is misconfigured.

You will need to configure bind to include:

    zone "16/20.168.192.in-arpa.arpa" {
        type master;
        file "/path/to/a/new/16.168.192.in-arpa.arpa-db-file";
        allow-update {  key copy-this-from-the-other-reverse-zone; };

the new db file should be something like:

    $TTL 2d ; 172800
    $ORIGIN 64/
    @            IN  SOA   ns1.example.com. hostmaster.example.com. (
                          2003080800 ; serial number
                          3h         ; refresh
                          15m        ; update retry
                          3w         ; expiry
                          3h      ; nx = nxdomain ttl
          IN  NS      ns1.example.com.
          IN  NS      ns2.example.com.

For more information on bind and reverse lookup, see this link where i learned everything i know about bind

  • if i configure "16.168.192.in-arpa.arpa" (without /20), will it work? – Rajnish Kumar Soni May 30 '19 at 15:08
  • 1
    No, then it only will work for 192.168.16.* But you could configure a zone for 22.168.192.in-arpa.arpa in addition to 21.168.192.in-arpa.arpa and it will probably work as long as the key is the same. – feitingen May 30 '19 at 20:49
  • Thanks understood the point. – Rajnish Kumar Soni May 31 '19 at 6:08

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