Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community!

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Development Tools Technology Foundations DNS Basics Domain Name Rules

Matt Varner
Matt Varner
5,373 Points

IPv4, IPv6 and Domain Name Limits

Just off the cuff here, I am wondering if the domain name rules Jason Seifer is highlighting in this informational survey of the subject are separated, contextually, from the network protocol(s) that eventually is/are utilized in the transfer of the packet information.

That is...if and when devices fully use the IPv6 protocol (as opposed to co-existing with the older IPv4), will that also mean an eventual change in the current limits of some domain name rules Jason mentions in the video:


  • 253 character (ASCII-only) limit for a domain name
  • 127 domain levels
  • Each level having a limit of 63 characters
  • LDH (letters, digits, hyphens)

1 Answer

Hey Matt,

Domain naming restrictions and IPv4/IPv6 stuff are not directly related. IPv6 is already in pretty widespread use, but even in an IPv6-only world, DNS as we know will still work the same. That's not to say though that domain naming rules never change. For example,

253 character (ASCII-only) limit for a domain name

This isn't strictly true anymore. Here's a Wikipedia article about internationalized domain names that support unicode characters.

Matt Varner
Matt Varner
5,373 Points


Thanks for the link. It's a good read.

So, the network protocol and the DNS rules are separate, contextually. Got it.

As for the internationalization of addresses, the way I read the content of the article is that it's sort of an ad hoc solution, limited in use to applications that will do the translation back and forth from and to ASCII, with the algorithm failing if its output does not conform to the normal DNS rules - so, technically, the rules are still 'strictly true,' it's just we're developing some tools to try to get around the limits at the level of the user experience (via a compatible browser/addon)

In fact, it seems that it puts more pressure (albeit, just a handful of characters) on the developer in a region that makes use of this solution because the addition of the "ACE prefix" (xn--) just further reduced the number of characters each level can have.

Still, kind of interesting stuff.