<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Apr 17, 2018 at 12:23 AM, Yonghua Peng <span dir="ltr"><<a href="mailto:ypeng@gmx.net" target="_blank">ypeng@gmx.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I saw some domains who have auth name servers in different TLDs.<br>
such as,<br>
<br>
;; ANSWER SECTION:<br>
<a href="http://gmx.net" rel="noreferrer" target="_blank">gmx.net</a>. 84558 IN NS <a href="http://ns-gmx.ui-dns.de" rel="noreferrer" target="_blank">ns-gmx.ui-dns.de</a>.<br>
<a href="http://gmx.net" rel="noreferrer" target="_blank">gmx.net</a>. 84558 IN NS <a href="http://ns-gmx.ui-dns.biz" rel="noreferrer" target="_blank">ns-gmx.ui-dns.biz</a>.<br>
<a href="http://gmx.net" rel="noreferrer" target="_blank">gmx.net</a>. 84558 IN NS <a href="http://ns-gmx.ui-dns.com" rel="noreferrer" target="_blank">ns-gmx.ui-dns.com</a>.<br>
<a href="http://gmx.net" rel="noreferrer" target="_blank">gmx.net</a>. 84558 IN NS <a href="http://ns-gmx.ui-dns.org" rel="noreferrer" target="_blank">ns-gmx.ui-dns.org</a>.<br>
<br>
;; ADDITIONAL SECTION:<br>
<a href="http://ns-gmx.ui-dns.biz" rel="noreferrer" target="_blank">ns-gmx.ui-dns.biz</a>. 163883 IN A 217.160.81.199<br>
<a href="http://ns-gmx.ui-dns.com" rel="noreferrer" target="_blank">ns-gmx.ui-dns.com</a>. 258650 IN A 217.160.82.199<br>
<a href="http://ns-gmx.ui-dns.de" rel="noreferrer" target="_blank">ns-gmx.ui-dns.de</a>. 163237 IN A 217.160.80.199<br>
<a href="http://ns-gmx.ui-dns.org" rel="noreferrer" target="_blank">ns-gmx.ui-dns.org</a>. 163744 IN A 217.160.83.199<br>
<br>
And this,<br>
<br>
<a href="http://easydns.com" rel="noreferrer" target="_blank">easydns.com</a>. 600 IN NS <a href="http://dns4.easydns.info" rel="noreferrer" target="_blank">dns4.easydns.info</a>.<br>
<a href="http://easydns.com" rel="noreferrer" target="_blank">easydns.com</a>. 600 IN NS <a href="http://dns1.easydns.com" rel="noreferrer" target="_blank">dns1.easydns.com</a>.<br>
<a href="http://easydns.com" rel="noreferrer" target="_blank">easydns.com</a>. 600 IN NS <a href="http://dns2.easydns.net" rel="noreferrer" target="_blank">dns2.easydns.net</a>.<br>
<a href="http://easydns.com" rel="noreferrer" target="_blank">easydns.com</a>. 600 IN NS <a href="http://dns3.easydns.org" rel="noreferrer" target="_blank">dns3.easydns.org</a>.<br>
<br>
Is this best practices for hosting a domain?<br>
<br>
Thank you.<br><br></blockquote><div><br></div><div>If I am wrong, hopefully someone will correct me.</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div><br></div><div>I think that it is probably best not to use multiple TLD's, but it is a tradeoff.</div><div><br></div><div>-- </div><div>Bob Harold</div><div><br></div></div><br></div></div>