<div dir="ltr"><div>Mark has the right idea. The initial lookup will pull in multiple NS records (from the glue), but when the glue expires or the conditions for a NS record refresh are otherwise met, the number of records will drop down to one. Less than ideal.<br></div><div><br></div><div><br></div><div><div># dig @<a href="http://pdns1.ultradns.net">pdns1.ultradns.net</a> +norecurse +noall +authority <a href="http://aws.amazon.com">aws.amazon.com</a> NS</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-932.amazon.com">ns-932.amazon.com</a>.</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-923.amazon.com">ns-923.amazon.com</a>.</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-931.amazon.com">ns-931.amazon.com</a>.</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-912.amazon.com">ns-912.amazon.com</a>.</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-921.amazon.com">ns-921.amazon.com</a>.</div><div><a href="http://aws.amazon.com">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-911.amazon.com">ns-911.amazon.com</a>.</div></div><div><br></div><div><div># dig @<a href="http://ns-932.amazon.com">ns-932.amazon.com</a> +norecurse +short <a href="http://aws.amazon.com">aws.amazon.com</a> NS</div><div><a href="http://ns-932.amazon.com">ns-932.amazon.com</a>.</div></div><div><br></div><div><div># dig @<a href="http://75.75.75.75">75.75.75.75</a> +short <a href="http://aws.amazon.com">aws.amazon.com</a> NS # Comcast</div><div><a href="http://ns-921.amazon.com">ns-921.amazon.com</a>.</div></div><div><br></div><div><div># dig @<a href="http://8.8.8.8">8.8.8.8</a> +short <a href="http://aws.amazon.com">aws.amazon.com</a> NS # Google</div><div><a href="http://ns-924.amazon.com">ns-924.amazon.com</a>.</div></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 8, 2015 at 7:58 AM, Mark Jeftovic <span dir="ltr"><<a href="mailto:markjr@easydns.com" target="_blank">markjr@easydns.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I believe this is the entire set:<br>
<br>
$ dig +trace <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a><br>
<br>
[snip]<br>
<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-932.amazon.com" rel="noreferrer" target="_blank">ns-932.amazon.com</a>.<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-923.amazon.com" rel="noreferrer" target="_blank">ns-923.amazon.com</a>.<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-931.amazon.com" rel="noreferrer" target="_blank">ns-931.amazon.com</a>.<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-912.amazon.com" rel="noreferrer" target="_blank">ns-912.amazon.com</a>.<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-921.amazon.com" rel="noreferrer" target="_blank">ns-921.amazon.com</a>.<br>
<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a>. 7200 IN NS <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a>.<br>
;; Received 261 bytes from 204.74.108.1#53(<a href="http://pdns1.ultradns.net" rel="noreferrer" target="_blank">pdns1.ultradns.net</a>) in 170 ms<br>
<br>
<br>
but each nameserver is only returning it's own RR (I think)<br>
<br>
- mark<br>
<span class=""><br>
On 2015-12-08 7:35 AM, Valentin Bud wrote:<br>
> Hello Yonghua,<br>
><br>
> Fom where I am standing (.ro) things look differently, as it follows.<br>
><br>
</span>> ~$ dig +short <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a> <<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">http://aws.amazon.com</a>> ns in<br>
> <a href="http://ns-932.amazon.com" rel="noreferrer" target="_blank">ns-932.amazon.com</a> <<a href="http://ns-932.amazon.com" rel="noreferrer" target="_blank">http://ns-932.amazon.com</a>>.<br>
><br>
> ~$ dig +short <a href="http://ns-932.amazon.com" rel="noreferrer" target="_blank">ns-932.amazon.com</a> <<a href="http://ns-932.amazon.com" rel="noreferrer" target="_blank">http://ns-932.amazon.com</a>>. a in<br>
<span class="">> 52.16.221.207<br>
><br>
> I guess that Amazon has geo aware DNS configuration in place.<br>
><br>
> Also I can find the A IN for <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a><br>
</span>> <<a href="http://ns-911.amazon.com/" rel="noreferrer" target="_blank">http://ns-911.amazon.com/</a>> and it matches yours.<br>
><br>
> ~$ dig +short <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a> <<a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">http://ns-911.amazon.com</a>>. a in<br>
<span class="">> 207.171.178.6<br>
><br>
> Best,<br>
> Valentin<br>
><br>
> On Tue, Dec 8, 2015 at 2:10 PM Yonghua Peng <<a href="mailto:pyh@cloud-china.org">pyh@cloud-china.org</a><br>
</span><span class="">> <mailto:<a href="mailto:pyh@cloud-china.org">pyh@cloud-china.org</a>>> wrote:<br>
><br>
> Hi,<br>
><br>
> As you see,<br>
><br>
</span>> ~$ idig <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a> <<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">http://aws.amazon.com</a>> ns<br>
> <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a> <<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">http://aws.amazon.com</a>>. 587 IN NS<br>
> <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a> <<a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">http://ns-911.amazon.com</a>>.<br>
><br>
> ~$ idig <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a> <<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">http://aws.amazon.com</a>> soa<br>
> <a href="http://aws.amazon.com" rel="noreferrer" target="_blank">aws.amazon.com</a> <<a href="http://aws.amazon.com" rel="noreferrer" target="_blank">http://aws.amazon.com</a>>. 60 IN SOA<br>
> <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a> <<a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">http://ns-911.amazon.com</a>>.<br>
> <a href="http://root.amazon.com" rel="noreferrer" target="_blank">root.amazon.com</a> <<a href="http://root.amazon.com" rel="noreferrer" target="_blank">http://root.amazon.com</a>>. 1449536989 3600 900 7776000 60<br>
><br>
> ~$ idig <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a> <<a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">http://ns-911.amazon.com</a>><br>
> <a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">ns-911.amazon.com</a> <<a href="http://ns-911.amazon.com" rel="noreferrer" target="_blank">http://ns-911.amazon.com</a>>. 197 IN<br>
<span class="">> A 207.171.178.6<br>
><br>
> Do you know why this well known domain has only one nameserver, and it<br>
> seems the nameserver has only one IP?<br>
><br>
> Thx.<br>
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</span><span class="HOEnZb"><font color="#888888">--<br>
Mark Jeftovic, Founder & CEO, easyDNS Technologies Inc.<br>
Company Website: <a href="http://easydns.com" rel="noreferrer" target="_blank">http://easydns.com</a><br>
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