ds

.arpa

Generic top-level domain

WHOISinfrastructure zone

Nobody outside the registry can register here. .arpa is infrastructure, not a place names are sold. ds reports names here as PRIVATE rather than AVAILABLE, and leaves the zone out of --tld all unless you pass --private include. See Brand and reserved TLDs.

Registration
Closedno public names
Operator
Infrastructure zone
Lookup
WHOISanswers for it
DNSSEC
Signed1 DS record in the root
Level
Secondmybrand.arpa

Check a name

Names under .arpa cannot be registered, but ds will still tell you what the registry says.

Fills the command and the registrar links below in with your own name. The page is static — nothing is looked up here, and nothing you type leaves the browser.

ds mybrand --tld arpa

Add --where for the registrars and the registry's rules, --registry for the server that answered, or --all-info for everything at once.

What it costs

No registrar in the price table bundled with ds quotes .arpa, so the CLI prints no figure beside it — one of 927 such TLDs. That is a gap in the table as often as it is a TLD nobody sells, though here it is neither: the zone is closed. See Prices for supplying your own table with --pricing-file.

Who can register

Nobody outside the registry — see the note at the top of this page.

How ds answers for it

RDAP first, WHOIS second — the same order for every TLD. .arpa has no RDAP service, so the answer comes from WHOIS text on port 43.

WHOIS
whois.iana.orgQueried on port 43, from the bundled whois.json. The name is called free when the reply contains 0 objects — text matching, which is why RDAP is preferred where it exists.

ds mybrand --tld arpa --registry prints whichever of these answered. If a bundled WHOIS host has gone stale, IANA is asked who serves .arpa today. See Accuracy notes.

The registry

From IANA's delegation record for .arpa. .arpa is the infrastructure TLD.

Run by
Internet Architecture Board (IAB)Based in United States of America. Delegated 1985-01-01, record last updated 2023-11-27.
Registry site
www.iana.orgWhere the registry documents .arpa — its rules, its accredited registrars, and any launch phases. Not a shop: registries sell wholesale to registrars, not to you.
Published services
whois.iana.orgWhat the registry itself tells IANA it runs. They agree with what ds asks.
Name servers
a.ns.arpab.ns.arpac.ns.arpad.ns.arpae.ns.arpaf.ns.arpag.ns.arpah.ns.arpai.ns.arpak.ns.arpal.ns.arpam.ns.arpaThe 12 authoritative servers for the .arpa zone — what the root delegates to. Nothing ds queries directly; they are what makes a registered name resolve.

What it is

Derived from the root zone and ICANN's registry list — each one is a fact with a source.

  • infrastructure IANA Root Zone Database types it "infrastructure"

In the root zone

The delegation itself, read out of the root zone — serial 2026090900, on 2026-09-09. The registry section above is IANA's record of what .arpa was delegated to; this is what the root actually answers with when a resolver asks it where .arpa lives.

Delegated to
  • a.ns.arpa198.41.0.42001:503:ba3e::2:30
  • b.ns.arpa170.247.170.22801:1b8:10::b
  • c.ns.arpa192.33.4.122001:500:2::c
  • d.ns.arpa199.7.91.132001:500:2d::d
  • e.ns.arpa192.203.230.102001:500:a8::e
  • f.ns.arpa192.5.5.2412001:500:2f::f
  • g.ns.arpa192.112.36.42001:500:12::d0d
  • h.ns.arpa198.97.190.532001:500:1::53
  • i.ns.arpa192.36.148.172001:7fe::53
  • k.ns.arpa193.0.14.1292001:7fd::1
  • l.ns.arpa199.7.83.422001:500:9f::42
  • m.ns.arpa202.12.27.332001:dc3::35
The 12 name servers the root hands out for .arpa, with the glue addresses that come with them — every one of them answers over IPv6. None of this is what ds queries: these servers know which names exist, not who registered them.
DNSSEC
Signed — 1 DS record in the root
  • key 42581RSA/SHA-256 · SHA-256F28391C1ED4DC0F151EDD251A3103DCE0B9A5A251ACF6E24073771D71F3C40F9
Each one is a fingerprint of .arpa's own signing key, published by the root and signed with the root's key — which is how a resolver that trusts only one key can prove an answer under .arpa came from its registry and was not tampered with in transit. It says nothing about who owns a name or whether one is free.

Ask the root yourself — no registry involved, and the same records this section was built from: dig +norec @a.root-servers.net arpa. NS and dig +norec @a.root-servers.net arpa. DS.