AcuRite Access Not Using My Network DNS Settings After A Few Days?

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I have two AcuRite Access devices on my network. One is transmitting to Weather Underground and myAcuRite (Device 1) and the other is only transmitting to myAcuRite (Device 2).

They both seem to be transmitting just fine.

The problem or question I have surrounds their use of DNS. When I first boot both devices they will use my local DNS server to look up the connection information, but after about a day or two Device 1 will continue to send data to myAcuRite and Weather Underground, but it is not using my DNS server (I can see this in the server logs). Device 2 is still using my local DNS as expected.

Why is Device 1 no longer using my DNS server? What DNS server *is* it using?

Both devices are reporting Firmware Version 046

I purchased both Access devices at the same time when upgrading from my old smartHUB and they were sent to me by AcuRite directly, not a third-party seller, so as far as I am concerned they are still "new" (less than one month old).
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Todd

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Posted 3 months ago

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George D. Nincehelser

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The logs aren't saying what DNS server is being used?  Either by name or IP number?
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Todd

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My DNS server will tell me when a device uses it, but my DNS server won't tell me if a device is reaching out to another DNS server. Hopefully that makes sense.

Unfortunately I can't see on the Access device itself what DNS server it is set to use. The IP address and DNS are assigned by my router dynamically. (I have a DHCP reservation for both Access devices). I don't see a way on the Access itself to set or view the network options.
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George D. Nincehelser

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Is there any possibility you may have another DHCP server running on your network that might have different DNS information?

Short of putting up a network sniffer to see what's going on, this could be tough to debug.
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Todd

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Only one DHCP server on the network (my router), and no other devices seem to have this issue.

I know IoT devices tend to be black boxes, but I thought maybe someone here may have more insight into how these work, being that it's a place for AcuRite equipment. ;)
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George D. Nincehelser

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It's probably just normal DNS operation.  You could look at your DHCP and DNS server settings to try to reason out exactly what is being sent to the Access, but it would be a lot easier to look at the network traffic and see what is forcing the Access to try something other than the local DNS server.  

Just guessing, but I suspect the Access didn't get a response from your local DNS server, so it went down the list to one of your ISP DNS servers directly.
(Edited)
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Todd

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There are only two DNS servers being assigned by my router, and both are internal to my network. I don't know what the Access device is using as a fallback, but whatever it is, it's circumventing what my network is telling it to use. I reset the offending Access device yesterday and for now it's using the correct DNS server, but I am fairly certain it will stop using my DNS again. I'm going to keep an eye on how long it takes or if an "event" is causing it to divert to something else. What's weird is it's only one Access device, not both of them.
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John Z

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Todd,

Swap the two Access devices. See if the DNS behavior sticks with the one sending rapid fire traffic to WU or follows the hardware. Traffic to MyAcuRite alone is far less frequent than to WU. I suspect George is correct that at times your router gets tired of waiting and moves on.
(Edited)
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Todd

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That makes sense in theory, but my old smartHUB was a lot chattier than the new Access devices are (I think that's part of why AcuRite changed the design, tremendously less traffic), and that never went rogue on its DNS settings.
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Todd

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I think I've narrowed down what is happening. When my DNS server updates (it updates a block list weekly, or I can do it manually), it slows down on being responsive. Other devices on the network revert to the secondary DNS device and use that. After the primary DNS server is back to normal (a few minutes), they resume using that.

When this happened in the past my old smartHUB would switch to the secondary DNS and then use that. When the secondary DNS was too slow for it, it would switch back to my primary DNS.

It seems like with the Access, it is not looking for my secondary DNS at all. When the primary DNS is "slow" or "down" it reverts to something else entirely, but I'm not sure what.

I've seen other devices only have one DNS server that they use, and then if it's not available they either wait, or fail. They don't just go do their own thing when it's not available.
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George D. Nincehelser

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How a nameservice fails-over depends on the device.

For example, unix systems often use a "nsswitch.conf" file which sets the priority for name service switching.  Often this is set to try DNS first, NIS second, and if that fails use local configuration files.

Without a sniffer to analyze what's going on, it's difficult to verify if this is actually happening, but "doing its own thing" for name resolution purposes is not an illegal operation. 
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Todd

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Oh I understand it's not "illegal" and plenty of devices use their own DNS (Amazon devices are notorious for this). I was hoping maybe someone from AcuRite would chime in and confirm the behavior, but they seem uninterested. :-/
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George D. Nincehelser

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The support folks here don't often get into the nitty-gritty of the deep technical issues.

They leave a lot of things for us to figure out ourselves. ;)