[AusNOG] Endlessly resetting modems after DNS outage

[Narelle]

And none of these fail over to ns2 in the event of losing ns1?

Presumably also load on a large scale network restore would also cause
congestion reaching the DNS, hence more issues with reachability.


On Fri, May 27, 2016 at 3:10 PM, John Edwards <jaedwards at gmail.com> wrote:

> A problem with short TTL's in embedded devices is that they then need to do
> a DNS lookup nearly every time they send a heartbeat - instead of just
> checking the resolver cache from the last lookup. This works fine in the
> lab, but in the real world it means that a single lost packet in a UDP DNS
> lookup can cause a TCP heartbeat process to fail.

On Fri, May 27, 2016 at 3:05 PM, Gavin Tweedie <gav at narx.net> wrote:
> Some consumer CPE do a dns lookup or ping to a.root-servers.net to determine
> if the internet is working once they are assigned an IP address. This
> triggers the "internet" light on the modem to go on (as opposed to the DSL
> SYNC light) and any iptables/firewall/nat/other processes to kick in.
>

Regards

N

-- 


Narelle
narellec at gmail.com