[dns-operations] auth servers in different TLDs

Bob Harold rharolde at umich.edu
Tue Apr 17 13:46:01 UTC 2018

On Tue, Apr 17, 2018 at 12:23 AM, Yonghua Peng <ypeng at gmx.net> wrote:

> I saw some domains who have auth name servers in different TLDs.
> such as,
> gmx.net.                84558   IN      NS      ns-gmx.ui-dns.de.
> gmx.net.                84558   IN      NS      ns-gmx.ui-dns.biz.
> gmx.net.                84558   IN      NS      ns-gmx.ui-dns.com.
> gmx.net.                84558   IN      NS      ns-gmx.ui-dns.org.
> ns-gmx.ui-dns.biz.      163883  IN      A
> ns-gmx.ui-dns.com.      258650  IN      A
> ns-gmx.ui-dns.de.       163237  IN      A
> ns-gmx.ui-dns.org.      163744  IN      A
> And this,
> easydns.com.            600     IN      NS      dns4.easydns.info.
> easydns.com.            600     IN      NS      dns1.easydns.com.
> easydns.com.            600     IN      NS      dns2.easydns.net.
> easydns.com.            600     IN      NS      dns3.easydns.org.
> Is this best practices for hosting a domain?
> Thank you.
If I am wrong, hopefully someone will correct me.

If your domain is under ".com", then it won't be reachable if all the .com
NS servers are unreachable, even if you have NS servers in other TLD's,
because resolvers won't be able to query the parent zone.  Except for short
outages while the parent zone info is cached.  So I don't think it really
helps much.

On the other hand, anyone who compromises any of the TLD's that you use for
NS records would be able to compromise your domain, so it could be a
disadvantage to use several TLD's.

The one benefit would be that using more TLD's means a larger pool of
anycast servers that hold the parent zones of you NS servers.

I think that it is probably best not to use multiple TLD's, but it is a

Bob Harold
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