What is a Name Collision?
Name Collision refers to the situation in which a resource name that is intended to be resolved in one naming system is inadvertently resolved in a different naming system, potentially leading to unexpected behavior such as communication being disrupted or redirected from its intended recipient.
Name collisions are not new. The introduction of any new domain name into the DNS, whether a generic TLD, country code TLD, or second-level domain name, creates the potential for name collisions. However, queries for un-delegated TLDs at the root level of the global DNS have received renewed attention because applied-for new gTLD strings could be identical to name labels used in private networks or other naming systems. A secure, stable, and resilient Internet is ICANN's number one priority. Therefore, we've made a commitment to the Internet community to launch a substantial effort to mitigate and manage name collision occurrence.
How will the risk of Name Collisions be mitigated in the New Generic Top-Level Domain (gTLD) Program: Next Round?
It is unlikely that domain name collisions will affect significant numbers of corporate network operators or Internet users. However, ICANN considers it essential that it does everything possible to minimize potential impact and to offer clear advice on dealing with the issue.
As part of ICANN's New Generic Top-Level Domain (gTLD) Program: 2026 Round, the Name Collision project's purpose is to implement the necessary functionality and procedures to assess and mitigate the risk for name collisions between the global DNS and other naming systems using the Name Collision Risk Management framework, following recommendations from the Name Collision Analysis Project Study Two Report, as directed by the ICANN Board on 7 September 2024 (2024.09.07,10).
Key Updates and Upcoming Milestones:
| Date | Description |
|---|---|
| 20 October 2025 to 22 December 2025 | The IPv6 Research Study Proceeding was opened, which addresses the issue of name collisions in the DNS ahead of the 2026 Round of the New gTLD Program. The study focuses on extending ICANN's "controlled interruption" mechanism, previously implemented using the IPv4 address 127.0.53.53 into the IPv6 realm, given the growing adoption of IPv6 (> 40 % of hosts). If you are interested in reading the study or would like to access the public comments repository, please visit https://www.icann.org/en/public-comment/proceeding/name-collision-ipv6-research-study-20-10-2025 |
| 29 January 2026 to 16-March 2026 | The Name Collision Procedure Documentation Proceeding was opened. These procedures were developed to describe how the evaluations for Initial Assessment, Temporary Delegation, and the High-Risk String Mitigation Plan will be carried out. The procedures are supported by the impact-based classification model for identifying high-risk strings. If you are interested in reading the documentation or would like to access the public comments repository, please visit https://www.icann.org/en/public-comment/proceeding/name-collision-procedure-documentation-29-01-2026 |
| 04 February 2026 | The Name Collision Observatory (NCO) tool was developed to allow potential gTLD applicants, or other community members to display historical DNS magnitude data – a DNS popularity score – for top-level domain strings. The magnitude data presented is provided by a number of root server operators, as well as by some recursive resolver providers. The data may help applicants to assess the risk of Name Collision. It should be noted that the magnitude data for an applied-for string is only one of several factors that will be considered in the Name Collision Initial Assessment. Both quantitative data and qualitative aspects will be considered when assessing the risk associated with that string in the 2026 Round TLD application process. Applicants should not assume that if this tool indicates a low volume of queries for a string, the string will be assessed during the application process as safe to be delegated. For more information see the "Name Collision" section of the latest version of the Applicant Guidebook. The NCO is available at https://newgtldprogram-nco.icann.org/ |
How are Name Collisions Identified? 127.0.53.53
127.0.53.53 is a special IPv4 address that will appear in system logs alerting system administrators that there is a potential name collision issue, enabling a quick diagnosis and remediation. The "53" is used as a mnemonic to indicate a DNS-related problem owing to the use of network port 53 for the DNS service.
System administrators that encounter a system error due to name collision are encouraged to take the following steps:
- Report the problem to ICANN »
Instances where there is a reasonable belief of demonstrable, severe harm as a consequence of a name collision should be reported. - Read the Guide to Name Collision Identification and Mitigation for IT Professionals (version 1.1) [PDF, 476 KB] and implement the measures outlined therein.
- Spread the word about the potential for name collision occurrence and mitigation in your professional circle.