WAN failover - DNS requests consumed data allowance.
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I have a WAN failover setup with 4G as backup. It has been added to a group as a lower tier. Gateway is configured for packet loss.
Only two devices use the gateway group in the rules, Tado and Google nest.
I’ve not seen any traffic exiting over that interface, but there are DNS states open. Makes sense as two dns servers configured, one assigned to each gateway.
2GB allowance and it’s been used in 20 days, would you expect DNS requests to consume this.. (I know device request dependant etc).
Default gateways are set to primary WAN, not auto.
I must have something miss configured?
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@mikey_s 2GB is a lot of dns requests... But sure could see that happening.
Lets do some math for curiosity sake. Does your 2GB count both up and down traffic? Lets say a dns query is 500 Bytes total up and down.. Doubled what I saw in simple sniff just for cushion in our math. You would have to
So that is what 4 million queries? My whole network, lots of clients in last 24 hours have done
Now keep in mind that I change the min ttl to 1 hour, so this will be skewed.. Many ttls these days are short 60 seconds, 5 minutes.. So sure number of queries will be up.. So if you were doing 10x that or 280k queries a day.. Doesn't take long to get to 4million queries.. A 5 minute ttl if something is being asked for all the time would equate to lot of queries, and if something is banging its head looking for something.. Shoot I have had a single alexa do 2Million queries in 24 hours before.
Lets not forget the pings for monitor, default is what 2 a second. Small but there will be some data there. Even with zero byte payload.
So yeah I would think it quite possible to use up a 2GB of bandwidth without really even moving any traffic at all.
I would suggest you do a sniff for say an hour of traffic out your lte interface.. With no clients really even using it.. Then do some math to how long it would take to eat that 2GB up.
With such a low amount data limit to work with.. I would prob make that failover a manual process.. And I wouldn't let it do dns queries out it until such time that is your only connection. And I would for sure limit the min ttl to something less than many sites use these days of those insanely low ttls.. And look to see how much data just monitoring is using..
So just adding up the pings, and have payload set to 0...
30 seconds is 6KB, so what is that like 17MB a day just in pings, or 30 days like 500MB.. which would be 1/4 of your monthly quota just in monitor if the gateway is up.
LTE can make for a great backup, but if you have a low data quota - it would be quite easy to suck that up all with just background noise like dns and monitoring to be honest. Depending on what counts against your quota..
