[dns-operations] root? we don't need no stinkin' root!

Mark Allman mallman at icir.org
Wed Dec 18 19:51:47 UTC 2019

>> On 11 Dec 2019, at 12:51, Stephane Bortzmeyer <bortzmeyer at nic.fr> wrote:
>> IMHO, this is by far the biggest issue with your proposal: TLDs change
>> from one technical operator to another and, when it happens, all name
>> servers change at once.
> That’s not correct.
> In principle, they could all change at once, In reality, they
> don’t.

I wondered about this.  So, I crunched across our corpus of root
zone files, which spans from Apr 28 2009 to now (I stopped crunching
on Dec 11 2019).  We have one zone file per day (we miss a day here
or there due to glitches, but not many, the corpus is 3,500 days
long).  I found:

  - There are 1,578 TLDs that appear in the root zone file at some
    point in the last 10 years.

  - Of those, 1,139 (72.2%) have at least one nameserver (by IP)
    that is constant over the entire period the TLD is active.  (I'd
    have not guessed it was this high!)

  - For the remaining 439 TLDs, for each day the TLD was active I
    calculated how many days into the future would it be until none
    of the current set of nameservers (by IP) would no longer be
    listed.  For each TLD I took the minimum value.  That shows:

    + 173 TLDs (or 11.0% of all TLDs) at some point have a switch as
      Stephane describes.  I.e., there are no common IP addresses in
      the nameserver set between day X and day X+1.

    + Another 107 TLDs (or 6.8% of all TLDs) had a point where a
      zone file become outdated more in [2,7] days.

    + 75 TLDs (or 4.8% of all TLDs) had a point where a zone file
      become outdated in [8,30] days.

    + 84 TLDs (or 5.4% of all TLDs) only ever became outdated after
      more than 30 days.



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