RE: How common is lack of DNS server diversity?
From: Sean Donelan [mailto:sean@donelan.com] Sent: Friday, January 26, 2001 7:01 PM
Mice and Men found that 38% of the .COM domains surveyed had all their name servers on the same subnet. And 75% had one or more configuration errors.
Distribution requirements,of root name servers, is dependent on where in the tree you live. dot root servers should be spread out, as they are authoritative for everything. TLD root servers should also be spread out, they are authoritative for many things. SLD root servers need not be spread out so much, they are authoritative for few things. 3LD root servers don't need to even leave their AS, if the AS is down the servers, they are authoritive for, are probably also down. 4LD root servers ... who cares? More interestingly, how many root servers allow recursive lookup?
On Sat, 27 Jan 2001, Roeland Meyer wrote: [snip]
dot root servers should be spread out, as they are authoritative for everything. TLD root servers should also be spread out, they are authoritative for many things. SLD root servers need not be spread out so much, they are authoritative for few things. 3LD root servers don't need to even leave their AS, if the AS is down the servers, they are authoritive for, are probably also down. 4LD root servers ... who cares?
ok, these are obviously generalisations and most DNS-savvy folk would agree with a pinch of salt and a mumble about special cases. e.g. (in particular) {\8}.in-addr.arpa should be considered a TLD in this context.
More interestingly, how many root servers allow recursive lookup?
a quick looping probe shows that none of them do, nor the gTLD servers (phew!) although L.ROOT-SERVERS.NET and H.GTLD-SERVERS.NET are unreachable from my view. Preparing an accurate list of all TLD servers glued in the root zone will take a little longer. joshua
participants (2)
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Joshua Goodall -
Roeland Meyer