Two DNS servers with one IP address

Bill Campbell freebsd at
Fri Jun 27 10:32:02 PDT 2003

On Fri, Jun 27, 2003 at 07:34:49AM +0100, Jez Hancock wrote:
>Can anyone confirm that it's no longer a requisite to provide 2
>distinct DNS servers for a domain you register?  I say no longer
>because as I understand it there was a time when 2 distinct nameservers
>were required...

Not having multiple servers may be OK for vanity domains, but certainly
isn't advisable if one wants reliable DNS.  It's a Good Idea(tm) to have
secondary servers geographically separated so that local problems don't
take out all the DNS for a domain (e.g.  earthquakes, floods, etc.).  One
of the more amusing examples of this occurred within the last two years
when all of Microsoft's DNS failed.  M$ had multiple servers all right, but
they were all on the same class C network so a routing problem brought them
all down.

Similar reasoning applies to having multiple MX (Mail eXchange) servers for
a domain.  Backup MX servers get a bit more complicated though if one is
doing any spam blocking as all the backup servers have to have at least as
restrictive rules as the primary or the spammers just get to you through
the back door.

>Also, in the case an admin has only one auth nameserver for a domain but
>a registrar _requires_ you list two, what is the best strategy for
>listing the second nameserver? Is there any way to avoid using a third
>party DNS provider as your secondary nameserver (providing some sort of
>dummy listing)?

Do you have local user groups, ISPs, or businesses that run DNS servers
that would provide backups?  We provide backup DNS for most of our
customers including some fairly large regional ISPs with hundreds of
domains.  It's frequently possible to set up reciprocal deals with others.

INTERNET:   bill at Celestial.COM  Bill Campbell; Celestial Software LLC
UUCP:               camco!bill  PO Box 820; 6641 E. Mercer Way
FAX:            (206) 232-9186  Mercer Island, WA 98040-0820; (206) 236-1676

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