Just to clarify, let's assume that you maintain zone <a href="http://example.be">example.be</a>. Let's also say that in .be zone TTL for your NS'es is <span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"></span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"">86400 and </span>TTL for NS'es in your zone is <span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"></span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"">345600.<br>
<br>In such scenario the latter will be cached by resolver because it is the authoritative data. For some resolver implementations this behaviour can be overrided.<br></span><br>To replace nameserver with new one I would do the following:<br>
1. set up new server;<br>2. send updates to parent zone;<br>3. wait for TTL mentioned in my zone (for example above - <span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"></span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"">345600);</span><br>
4. shut down old server(s).<br><br><div class="gmail_quote">2012/6/5 hugo hugoo <span dir="ltr"><<a href="mailto:hugobxl@hotmail.com" target="_blank">hugobxl@hotmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">



<div><div dir="ltr">
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Dear all,</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Can anyone clarify to me the use of the TTL for a NS record?</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Let’s take the example of a *.be domain.</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">A TTL value is present on both locations.</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"><span>1)<span style="font:7.0pt "Times New Roman"">   
</span></span></span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">In a <a href="http://dns.be" target="_blank">dns.be</a> server (for example <a href="http://x.dns.be" target="_blank">x.dns.be</a>): in my example here below, value is
</span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"">86400   </span>
<span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"></span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"><span>2)<span style="font:7.0pt "Times New Roman"">   
</span></span></span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">In the name server itself: in my example here below, value is
</span><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"">345600  </span>
<span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"></span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">If we plan to change the name server to be used for a certain domain, do we have to change the TTL in the <a href="http://dns.be" target="_blank">dns.be</a>?</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Is this possible?</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Is this value that all the cache servers use?</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">If yes…what about the TTL value of the name server itself?</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Thank in advance of any useful feedback,</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Hugo,</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><b><u><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">Example:</span></u></b></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">dig @localhost <a href="http://google.be" target="_blank">google.be</a> NS +trace</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">; <<>> DiG 9.6-ESV-R4 <<>> @localhost <a href="http://google.be" target="_blank">google.be</a> NS +trace</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">; (1 server found)</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">;; global options: +cmd</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://f.root-servers.net" target="_blank">f.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://g.root-servers.net" target="_blank">g.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://h.root-servers.net" target="_blank">h.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://a.root-servers.net" target="_blank">a.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://i.root-servers.net" target="_blank">i.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://b.root-servers.net" target="_blank">b.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://j.root-servers.net" target="_blank">j.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://c.root-servers.net" target="_blank">c.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://k.root-servers.net" target="_blank">k.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://l.root-servers.net" target="_blank">l.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://d.root-servers.net" target="_blank">d.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://m.root-servers.net" target="_blank">m.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">.                       502894  IN      NS      <a href="http://e.root-servers.net" target="_blank">e.root-servers.net</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">;; Received 436 bytes from 127.0.0.1#53(127.0.0.1) in 0 ms</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://m.ns.dns.be" target="_blank">m.ns.dns.be</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://x.dns.be" target="_blank">x.dns.be</a>.</span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://london.ns.dns.be" target="_blank">london.ns.dns.be</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://prague.ns.dns.be" target="_blank">prague.ns.dns.be</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://brussels.ns.dns.be" target="_blank">brussels.ns.dns.be</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">be.                     172800  IN      NS      <a href="http://amsterdam.ns.dns.be" target="_blank">amsterdam.ns.dns.be</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">;; Received 307 bytes from 198.41.0.4#53(<a href="http://a.root-servers.net" target="_blank">a.root-servers.net</a>) in 27 ms</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              86400   IN      NS      <a href="http://ns2.google.com" target="_blank">ns2.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              86400   IN      NS      <a href="http://ns1.google.com" target="_blank">ns1.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              86400   IN      NS      <a href="http://ns4.google.com" target="_blank">ns4.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              86400   IN      NS      <a href="http://ns3.google.com" target="_blank">ns3.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">;; Received 109 bytes from 193.190.135.4#53(<a href="http://brussels.ns.dns.be" target="_blank">brussels.ns.dns.be</a>) in 1 ms</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>
<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              345600  IN      NS      <a href="http://ns4.google.com" target="_blank">ns4.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              345600  IN      NS      <a href="http://ns1.google.com" target="_blank">ns1.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              345600  IN      NS      <a href="http://ns3.google.com" target="_blank">ns3.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="NL-BE"><a href="http://google.be" target="_blank">google.be</a>.              345600  IN      NS      <a href="http://ns2.google.com" target="_blank">ns2.google.com</a>.</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US">;; Received 173 bytes from <a href="tel:216.239.36.10%2353" value="+12162393610" target="_blank">216.239.36.10#53</a>(<a href="http://ns3.google.com" target="_blank">ns3.google.com</a>) in 18 ms</span></p>

<p><span style="font-size:9.0pt;font-family:"Verdana","sans-serif"" lang="EN-US"> </span></p>                                     </div></div>
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