This is a courtesy notification of an upcoming change to the nameserver set for the IN-ADDR.ARPA zone.
There is no expected impact on the functional operation of the DNS due to this change.
There are no actions required by DNS server operators or end users.

For more information about this work, please see


The IN-ADDR.ARPA zone is used to provide reverse mapping (number to name) for IPv4. The servers which currently provide authoritative DNS service for the IN-ADDR.ARPA zone are as follows:

On Wednesday 2010-02-16 processing will begin to change the nameserver set to the following, as described in RFC 5855:

  • A.IN-ADDR-SERVERS.ARPA (operated by ARIN)
  • B.IN-ADDR-SERVERS.ARPA (operated by ICANN)
  • C.IN-ADDR-SERVERS.ARPA (operated by AfriNIC)
  • E.IN-ADDR-SERVERS.ARPA (operated by APNIC)

The usual IANA process for a change in the ARPA zone involves a series of technical checks and the gathering of various authorisations, and may take several days to complete.

Following this, the IN-ADDR.ARPA zone will be dropped from root servers in two groups:

  1. Week of 2011-02-21 — 2011-02-25
    • B, C, E, G, I, M
  2. Week of 2011-02-28 — 2011-03-11
    • A, D, F, H, K, L

Individual root server operators will choose a time for the maintenance within their respective window and follow their usual procedures to carry out the change.

Courtesy notification will be sent to this list once this change has been fully implemented.