LAN: think about Reverse IP address mapping (.arpa)

[gwarser]

https://en.wikipedia.org/wiki/.arpa#Reverse_IP_address_mapping

• *.in-addr.arpa
• *.ip6.arpa

[AnAccountForReportingBugs]

Those addresses return domain names when given a PTR request. My understanding is that they are not supposed to return IP addresses to A or AAAA requests. I suppose someone could configure their DNS server to return an address, but that is probably not very common.

For example:

    $ dig +short A dns.google.
    8.8.8.8
    8.8.4.4
    $ dig +short A 8.8.8.8.in-addr.arpa.
    $ dig +short PTR 8.8.8.8.in-addr.arpa 
    dns.google.

That said, given that they don’t return addresses, it probably wouldn’t hurt either.