How many TLDs safely fit in the DNS?
Date: Wednesday April 09 2008, @11:37AM
Topic: The Big Picture

Simon Higgs writes "I recently came across the question "How many TLDs safely fit in the DNS?". It, was, not surprisingly, in the context of ICANN doing some due diligence with their $30 million budget and actually answering the same questions that the IAB have been cowering behind for over a decade. Well, here's my answer for it's 2 cents of bandwidth:

In all fairness to ICANN, the reason why I think it hasn't answered the question is because it simply DOES NOT have a calculator that can calculate a number that big. You would think that ICANN should be able to go down to the corner store in Marina Del Ray and buy one, just like all the other high speed networking physicists in the Admiralty building. But the number's so big even the mighty Google refused to calculate it until a just few days ago.

So what are these huge numbers that ICANN is hiding from us? Using the current ASCII-based character strings used in DNS we get the following big numbers:

* Number of possible TLDs = (36 * (37 * 10^63)) = 1.332 10^66

* Number of possible domain names = (36 * (37 * 10^255)) = 1.332 10^258

The .COM zone pales by comparison. It only has 70,000,000 domain names (7 * 10^7 domains). By comparing these numbers, we know that the DNS, which is also recursive (see RFC1591), can hold an awful lot more of everything. More domain names, more TLDs, and even more sub-domains.

My question, in response, is if IPv6 can increase the number of IP addresses exponentially, why can't the DNS be allowed to grow in a similar manner too?

It is clearly no problem, at least to the integrity of the name space, for ICANN to give out all the TLDs that have ever been requested since RFC882 was published in 1983. It might not even break 10^3 and that's a ridiculously small number in the grand scheme of things.

* For those wondering where all those numbers come from, there are 26 characters for A-Z, 10 characters for 0-9 plus the hyphen making 37 characters. Because you can't start a domain name with a hyphen, it limits the first character to a choice of 36 possible characters. The rest can choose from the full 37 possibilities."

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It's even bigger...
by SimonHiggs on Thursday April 10 2008, @10:17AM (#16977)
User #2898 Info
I've been taken to task by ex-ICANN Board member Karl Auerbach because the big numbers I reported in the article above are wrong. They are, for want of a better way of putting it, embarrassingly small.

It seems that those numbers apply only to the number of domain names that are 255 characters long or have a 63 character TLD suffix. Clearly, I missed all the domain names that are 2 to 254 characters long and all the TLDs that are 1 to 62 characters long. The name space even bigger than I thought and I was out by a few billion billion.

It turns out that the number of possible TLDs is a very large number that is 96 characters long and, if you are viewing on a *nix 80-character screen or in an email client, one that will wrap around the page.

It's clearly obvious that anytime a number wraps around the page, well, it's simply much too big for ICANN (or anyone else) to ever claim as a scarce resource.

45740948715197463019198522067201064982535022753971 2687373445461577228502491435130988231174974800 TLDs don't lie.
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