Doing a reverse lookup on a misconfigured host and I get this result
from dnsstuff.com
*Preparation*:
The reverse DNS entry for an IP is found by reversing the IP, adding it to "in-addr.arpa", and looking up the PTR record.
So, the reverse DNS entry for 200.76.108.68 is found by looking up the PTR record for
68.108.76.200.in-addr.arpa.
All DNS requests start by asking the root servers, and they let us know what to do next.
See How Reverse DNS Lookups Work <
http://www.dnsstuff.com/info/revdns.htm> for more information.
*How I am searching*:
Asking e.root-servers.net for 68.108.76.200.in-addr.arpa PTR record:
e.root-servers.net says to go to ns2.dns.br. (zone: 200.in-addr.arpa.)
Asking ns2.dns.br. for 68.108.76.200.in-addr.arpa PTR record:
ns2.dns.br [200.19.119.99] says to go to B.NS.MX. (zone: 76.200.in-addr.arpa.)
Asking B.NS.MX. for 68.108.76.200.in-addr.arpa PTR record:
b.ns.mx [200.23.179.1] says to go to dns6m.inext.net.mx. (zone: 108.76.200.in-addr.arpa.)
Asking dns6m.inext.net.mx. for 68.108.76.200.in-addr.arpa PTR record: Reports latam.rci.com. [from 200.76.111.202]
*Answer*:
200.76.108.68 PTR record: *latam.rci.com.* [TTL 86400s] [A=148.243.230.2] **ERROR** A record for latam.rci.com. does not point back to original IP.
Exim see this as the sender_host_name being blank instead of returning
the misconfigured reverse lookup. Is there any way to just return the
reverse lookup even if it is misconfigured?
