205.7.79.27.in-addr.arpa domain name pointer localhost

  • Inspecting the fail2ban log on a host I tried to get the domain-names for banned IPs.
  • Of course some could not be resolved and a lot resolved to dynamic addresses or just AWS.
  • Puzzlingly some of them (as the one in the title) come back with a pointer to localhost. including the dot.

I know that you may set localhost as part/label of a FQDN, but how is it possible to set localhost as FQDN in DNS?