Hello mark!

Saturday November 22 2014 18:33, you wrote to me:

 KvE>> It is my opinion, that a system that fails to update its
 KvE>> IP address for a prolonged period of time, is not an active
 KvE>> system.

 ml> that we were responding to... there were no IP addresses posted... only
 ml> FQDNs... it is possible that those domains are dynamic... if that's the
 ml> case, they cannot resolve until the system comes online and updates its
 ml> record at the dynamic domain provider... some call this DDNS... in any
 ml> case, it may be that those systems you posted were simply offline when you
 ml> ran your check...

 I am aware how DDNS works, I had a dynamic address in dnsalias.net from
 early 2001 till this spring, when the free use ended. That may sound cheap,
 but I had no real use for their service anymore. It was a nice service and
 you could also register your IPv6 address for the same hostname.

 I now, more or less have my own DDNS service. The box with the dynamic address
 also serves as a hidden primay domain server. It is verywell able to adapt
 when the IP address changes by it self.

 As for the simply offline when I made the check. I do believe in coincidence,
 but not when the process is repeated at different times of the day and over
 a period of a couple of days.

 And I never experienced that a DDNS service returned a hostname not found as
 soon as a system went off line. That can only happen if the system deregisters
 before doing so. I am not aware of any. Besides that would require very short
 retension times in the DNS cache system.

 With dyndns you were required to update your IP address within somthing like
 a week, so that would at least be the period a system can be down before
 a host not found is returned. In the end of the free use period dyndns
 required that you do a manual confirmation one every 4 weeks. That requirement
 was introduced mid 2013.

 The software that updated my IP address ran daily, but only at intervals did
 I get a mail, that it dit a factual update.

 You will now see that with the free DDNS service fro dyndns terminated, a
 significant amount  of hostnames from the nodelist using the domains of
 dyndns, apparently have their accounts terminated.

 There are now 151 nodes in the nodelist that return a hostname not found,
 day after day. I do not think the coincidence you describe above can be
 applied to to all of them. That would not be realistic.

 ml> i've never seen any that allow for a system to be down that long
 ml> before
 ml> issuing NXDOMAIN statuses... the provider i use will start doing issuing
 ml> NXDOMAIN within a few minutes of my system not updating its record...
 ml> either that or it will point to another IP but that's an optional
 ml> setting... or it was way back when and i haven't looked at it in many
 ml> years...

 It issues within a few minutes, it expires after more than a week.

Kees

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