What are the ways to mitigate domain name conflicts? Why do domain name conflicts occur?

Domain names are sometimes added to the global DNS root zone, such as when a country or region name changes, or when ICANN delegates a new TLD. Both categories of top-level domains have been added almost every year for more than two decades.

Historical records show that domain name collisions sometimes occur when TLDs are added to the DNS. Records also show that domain names from private namespaces have been leaked over the years, in some cases with very high frequency. History tells us that namespaces and domain name resolution for private networks are never as completely separate as administrators imagine, and queries for domain names that administrators expect to be resolved by internal name servers are sometimes sent to resolvers in the global DNS.

Network administrators sometimes choose domain names based on the assumption that the list of domain names in the global DNS root is immutable, but in fact, that list can change over time. For example, after Czechoslovakia joined the CS TLD about 25 years ago, many universities used to allow users to enter domain names ending in CS to query the search list of the computer science department, which used the university's domain name for full qualification, but because these domain names ending in CS were FQDNs in the global DNS at the time, these decisions led to uncertainty in domain name resolution when new TLDs were added to the root zone. Even though the global DNS root domain names often overlap with domain names in private namespaces (private TLDs or search lists), network administrators often forget to update the domain names in the global DNS root.

It is recommended that IT departments start mitigation efforts as soon as possible. While taking a "we'll do a better job with firewalls" stance can reduce some conflicts, it is impossible to avoid all conflicts. Similarly, while "we'll make sure users are assured of our name servers" or "we'll let remote workers use VPNs" may reduce some conflicts, it will make others more difficult to judge.

Name collisions occur regardless of the characters used in the domain name; however, the use of non-ASCII characters in private TLDs complicates conflict analysis. Resolvers may issue queries for these domain names in unpredictable ways and may not conform to Internet standards, making it more difficult to determine when a name collision occurs.

While the global DNS root eventually expands over time, domain names are usually added to the root. Each new TLD may conflict with domain names in private namespaces that accidentally leaked to the Internet. Organizations have been using domain names for years and run the risk of name collisions.

Note that adding new domain names to the DNS root does not and will never affect organizations that are already using FQDNs in the global DNS. These organizations are not aware of any changes when using DNS domain names because there are no name collisions. Only organizations using dedicated TLDs or using short unqualified domain name search lists (which allow you to enter a short unqualified domain name search list) will experience name collisions because the short domain name itself may be a valid domain name in the global DNS.