AS16285 ASN-UMN Technicheskaya Str.18b, Yekaterinburg, Russia

One address answers reverse DNS with the reverse-lookup name itself, pointing at nothing but the question.

What it's used for

• A carrier's regional network. Fifty-five prefixes announced from the Russian Federation, twenty-seven of them IPv6, forty-four thousand and thirty-two addresses, through three observed BGP neighbours.

Notable

• The AS handle is three initials and then a street name, a house number with a letter suffix, a city and a country. The routing label is a postal address, and the initials match nothing in the holder field.
• Every sampled block uses one scheme: a country code, the carrier's brand, and a full date, with dates spanning eleven years.
• All of them list the same two contacts, an operations centre abbreviated to three letters and the company under its full legal form.
• Two of eighteen queried addresses answered. One returns the special-purpose name that reverse lookups are asked under, with the address written backwards, so the answer is a restatement of the query.
• The other pairs a two-letter protocol abbreviation and the last octet with a town's name as the domain.
• Twenty-seven IPv6 prefixes against twenty-eight IPv4 blocks is close to parity between the protocols.

Interesting

• A reverse record answering with the reverse-lookup name is what a misconfigured zone produces: the server has been told to point the name at itself. It resolves, it means nothing, and nothing checks it.
• Initials in a handle that match no company are the previous operator. Regional carriers get absorbed and the label stays, because changing it needs a reason and keeping it needs none.