.TLD minimum number of nameservers rule

Chris Thompson cet1 at cam.ac.uk
Mon Dec 12 18:04:20 UTC 2011

On Dec 12 2011, Anand Buddhdev wrote:

>I suspect that most, if not all registries will require you to provide
>at least 2 name servers, because this is highly recommended in one of
>the RFCs (forget which one now).

This seems to go right back to RFC 882 (November 1983):

| The domain must provide redundant (i.e., two or more) name servers
| to provide the name to address resolution service.  These name
| servers must be accessible from outside the domain (as well as
| inside) and must resolve names for at least all the hosts in the
| domain.

RFC 1035 (November 1987) just mentions this in section 2.1 "Overview":

| Different parts of the domain space are stored in different name
| servers, although a particular data item will be stored redundantly
| in two or more name servers.

while RFC 2182 (July 1997), which I suspect is the one Anand had in
mind, says in section 5 "How many secondaries?":

| The DNS specification and domain name registration rules require at
| least two servers for every zone.

before going on to recommend more than two in most cases.

Chris Thompson
Email: cet1 at cam.ac.uk

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