dns cache beyond ttl - viasat / exede

Mon Oct 7 16:16:48 UTC 2019

  I've seen similar issues (years ago) where some ISPs didn't honour DNS
TTLs, and would instead cache the results a LOT longer.

On Mon, Oct 7, 2019 at 9:08 AM Mike <mike-nanog at tiedyenetworks.com> wrote:

> Hello,
>
>
>     I am moving a number of web sites from one colo to another,
> re-numbering them in the process, and I have run into an interesting
> issue I'd like to solicit feedback on.
>
>     My dns TTL's are all 300 seconds, and I have noticed that once I
> update the A records with the new addresses, most (but not all) web
> clients begin using the new address within 5 minutes or so. However,
> there is a persistent set of stragglers who continue accessing the
> site(s) on their old addresses for far in excess of this - up to a week
> in fact. And, what I have noted, all of these clients have something in
> common - they all appear to be satellite users of viasat/exede.  This is
> based on whois lookups of the ip addresses of the clients. Note, I am
> NOT expecting 'turn on a time' - just looking for clients to refresh
> within a reasonable time.
>
>        I am wondering if perhaps this is due to some kind of (known?)
> bug in the embedded dns cache/client in the client satellite modem, or
> if there is another plausible explanation I am not seeing. It compounds
> my problem slightly since I have to continue running the web sites at
> both the old and new addresses while these things time out I guess and
> it's just inconvenient.
>
>
> Thanks.
>
>
> MIke-
>
>
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