Updated for June 2015: Collision lists, and how to get a previously unreleased domain name

This post contains a lengthy explanation of collision lists and previously unreleased domain names. But if you’d like to just skip to finding out when previously unreleased domains will be released (grouped by date and TLD) go here.
The domain name industry has a habit of taking a simple concept and adding a bunch of acronyms, background knowledge, technical jargon, and unnecessary details, until the simple concept becomes inaccessibly complicated. Name collision issues are a good example of these tendencies. In an effort to get back to basics, here’s a simplified explanation of name collision issues* and how you can use them to your advantage.

First, a basic refresher of what you need to know before moving diving into name collisions:

SLD/TLD: SLDs are the strings to the left of the dot. TLDs are the strings to the right of the dot. For “Name.com,” Name is the SLD and COM is the TLD.

Registrant/Registrar/Registry: Domain names involve three main parties. The registrant buys and uses the domain name (that’s you!). The registrar makes TLDs available to the registrant (that’s Name.com!) from registries. The registry owns, manages, and makes the TLD available to registrars (for example, that’s Rightside for .NINJA and Verisign for .COM)

Public DNS: The backbone of the internet as most people know it. It’s the mechanism that causes Name.com to go to our homepage no matter who/where someone searches for Name.com.

ICANN: The nonprofit organization responsible for ensuring the stability and security of the internet. Oversees the New TLD program.

New TLDs: Starting in early 2014 hundreds of New TLDs were added to the public DNS. Next to legacy TLDs like .COM and .MOBI, registrants can now choose TLDs like .NINJA, .SOCIAL or .ROCKS, among 100s more.

Easy, right? Now for the fun stuff!

What is a name collision?

Name collisions occur when someone attempts to visit a private name space and is accidentally rerouted to the public DNS. For example, a local coffee shop has an internal company network on DenverHR.Coffee. This network is only accessible to employees and is used for internal purposes (HR, payment processing, inventory, etc.) Before .COFFEE became a New TLD, this network would work if the user was on the internal network and set up properly without issue. An employee could hypothetically type DenverHR.Coffee into their browser and visit the internal resource.

However, after the delegation of .COFFEE, it is possible that an employee who typed DenverHR.Coffee may be redirected to the public DNS system. Unlike the internal DenverHR.Coffee, the New TLD version of DenverHR.Coffee is in the public Domain Name System and could be owned by another party. An employee of the coffee shop may hit this public version accidentally and may not even be aware of the difference. In the worst case scenario, the user might even be maliciously deceived via a phishing site on the publicly accessible version. Additionally, if the local coffee shop used automatic processes via their internal DenverHR.Coffee, these processes may fail or also be rerouted.

It is worth pointing out that the issue of name collisions is not new. The delegation of any TLD in the past could have potentially resulted in name collision issues, although none were ever reported. However, with the delegation of 100s of New TLDs and some reports of name collision issues, several measures were put in place by ICANN to mitigate any possibility of collision.

How does this affect registrants of New TLDs?

 Name collision issues most often affect registrants in two ways:
1) SLD Blocks: It’s possible that during 2014 and the early part of 2015 you attempted to register a domain and were told that the domain was not available due to a name collision block. Since ICANN did not provide many alternatives or a concise path to resolving name collision issues, registry operators were forced to make thousands (and sometimes 10,000s) of SLDs unavailable in any given TLD at their launch.

And here’s the important part for you:

Some of these SLDs have recently been cleared by ICANN for registration. Many previously unavailable SLDs in TLDs like .CLUB, .TRADE, and .BUZZ have already been made available in the past few weeks. On Jan. 14th Rightside Registry—the operator behind TLDs like .NINJA, .SOCIAL, and .ROCKS—will be making over 100,000 previously blocked SLDs available for registration on a first-come, first-served basis. Opportunities like this provide registrants an opportunity to register short, relevant SLDs in the corresponding TLD. For a complete list of Rightside Registry’s previously blocked SLDs that are becoming available, download this spreadsheet.

2) Interruption: An alternative way that a TLD may have chosen to resolve this issue is through delegated interruption. Instead of not allowing the name collision-affected SLD to be registered, a registry operator could have chosen to allow registrants to register the domain. However, the domain is then required to be disabled for 90 days after registration. For example, this approach was used for .BIO and is currently being used in .OOO. Since 90 days has passed since the .BIO release, all name collision SLDs in that TLD are now resolving. Conversely, it is still possible to register .OOO names that are affected by name collision issues. While the registrant will have domain ownership rights of these domains, they will not be able to use the domain until the interruption period completes.

TL;DR version:

Name collisions occur when someone attempts to visit a private name space and is accidentally rerouted to the public DNS. These reroutes can be bad, but no one really knows how often they actually happen with adverse effects. As a registrant you may be temporarily blocked from a certain SLD, or a New TLD you purchase may not resolve for up to 90 days. You can take advantage of this process as SLDs formerly blocked due to name collisions issues become available.

*This article was prepared with the casual registrant in mind. There are a lot more intricacies, policies and data surrounding name collision issue. If you’re interested in diving down the rabbit hole, we recommend that you start here and here