dnsmasq reverse iplookup doesn't work without a ptr record in the config file

Question

i have dnsmasq setup in my server. For some security reasons, i am not allowed to modify the /etc/hosts file or create any additional hosts file to store the hostname and the ip addresses.

so in dnsmasq.conf file i have added the hostname and ip address ,

address=/node01.black.system/10.248.11.21

and when i type

nslookup node01.black.system

i get the resulting ip address. But it doesn't vice cersa. If i do

nslookup 10.248.11.21

i am getting server can't find...:NXDOMAIN

however , when i add a ptr record in the dnsmasq.conf file

ptr-record=21.11.248.10.in-addr.arpa., node01.black.system

and then if i type

nslookup 10.248.11.21

i am getting the resultant hostname. Is there a way for this to work both ways, without adding the ptr-record?

because there are like 100 nodes, which will need resolution either way in the server

Thank you

Answer 1

Perhaps you are looking for the --host-record directive which creates both an A and PTR record.

 --host-record=<name>[,<name>....],[<IPv4-address>],[<IPv6-address>][,<TTL>]
   Add A, AAAA and PTR records to the DNS...

e.g.

host-record=node01.black.system,10.248.11.21

Whereas according the the dnsmasq man page the address option is to define an IP returned for any address in a domain. It does not mention creating a PTR record.

 -A, --address=/<domain>/[domain/]<ipaddr>
   Specify  an  IP address to return for any host in the given domains. 
   Queries in the domains are never forwarded and always replied to with
   the specified IP address which may be IPv4 or IPv6.

Since you are prevented from modifying the /etc/hosts file or creating any additional hosts, the following may not apply to your situation; but I consider them useful and related. These two options allow defining hosts outside of the normal /etc/hosts and the dnsmasq config.

 -H, --addn-hosts=<file>
   Additional  hosts  file.  Read  the specified file as well as /etc/hosts. 
   If -h is given, read only the specified file. This option may be repeated for 
   more than one additional hosts file. If a directory is given, then
   read all the files contained in that directory.

 --hostsdir=<path>
   Read all the hosts files contained in the directory. New or changed files are 
   read automatically. See --dhcp-hostsdir for details.