For example, walldns provides a PTR record for 126.96.36.199.in-addr.arpa showing 188.8.131.52.in-addr.arpa as the name of IP address 184.108.40.206, and a matching A record showing 220.127.116.11 as the IP address of 18.104.22.168.in-addr.arpa.
walldns runs chrooted in the directory specified by the $ROOT environment variable, under the uid and gid specified by the $UID and $GID environment variables.
walldns listens for incoming UDP packets addressed to port 53 of $IP. It does not listen for TCP queries.
walldns rejects inverse queries, non-Internet-class queries, truncated packets, packets that contain anything other than a single question, queries for domains outside in-addr.arpa, and request types other than A, PTR, and *.
walldns does not include NS or SOA records with its responses.
walldns uses TTLs slightly over one week.