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ICANN Computer Incident Response Team


Phone: +1 310 3015800


ICANN CIRT is the corporate Computer Incident Response Team for the Internet Corporation for Assigned Names and Numbers.

ICANN CIRT is not a public IT helpdesk and will not respond to questions having to do with matters unrelated to ICANN internal corporate security such as spam or domain registration disputes.

If you wish to report a security issue involving your web domain, please contact your registrar directly. If you believe you are being attacked by IANA assigned IP addresses please visit this page: to, or send email to:


ICANN CIRT: ICANN Computer Incident Response Team
CIRT email: icanncirt [at] icann [dot] org
Mailing Address: ICANN
12025 Waterfront Drive, Suite 300 Playa Vista, CA 90094
Telephone/ Fax Voice: +1 310 301 5800 / Fax: +1 310 823 8649

Contacting ICANN Computer Incident Response Team

  • If you are investigating an incident where ICANN corporate resources are involved or at risk, please call: +1 310 301 5800 and ask for the IT Security team.
  • Confidential communications with the ICANN Computer Incident Response Team may be encrypted using the public key for ICANN CIRT:

CIRT Team PGP Key fingerprint = 5CDF B749 68F8 8E73 90D0 888D 539C 470B 90C0 967B

Name PGP ID Fingerprint
Geoff Bickers 5183DFCD 7021 759F 1CF3 FD93 2F32 9EF4 4CA3 492B 5183 DFCD
Connor Barthold D02D5334 6096 89C4 9733 8443 1E80 2A30 B0B9 3B0A D02D 5334
Brian Martin 74A96005 D79A D269 B7B8 51B1 B10B DFD9 5383 0942 74A9 6005
David Prangnell 3966687B 37D3 FED9 D627 8E34 1E26 CC12 297F FE37 3966 687B
David Closson 996AE2C6 1FC2 F065 830C F0E3 0161 13D6 62D7 1E58 996A E2C6
Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as"""" is not an IDN."