DNS misconfigured on switch

[Mike_Rapp]

We have been experiencing an issue where an 8-Port POE switch keeps rebooting about once every half hour/hour. On the Meraki dashboard it is reporting DNS is misconfigured. I have used the "Google machine" and also Meraki's knowledgebase with little to no assistance. Though I would through this here and see if anybody has any suggestions. 

[BHC_RESORTS]

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@Mike_Rapp wrote:

We have been experiencing an issue where an 8-Port POE switch keeps rebooting about once every half hour/hour. On the Meraki dashboard it is reporting DNS is misconfigured. I have used the "Google machine" and also Meraki's knowledgebase with little to no assistance. Though I would through this here and see if anybody has any suggestions. 

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Does the DNS misconfigure message only occur right at boot? As in, does it go away after a few minutes? I've noticed this on a variety of Meraki devices that they will initially complain about DNS, then "figure it out" and go 5x5.

For the reboots, anything interesting in the event log right before it reboots?  Have you seen it in person? My initial guess is a PoE device/cable that is bad and causing a surge (it happens) or a bad switch (also happens).

[MRCUR]

If the switch is rebooting and there isn't anything obvious in the event log, I'd suggest contacting Support. They have access to a much more robust event log that will likely indicate why the switch is really rebooting. 

[Mike_Rapp]

Thanks for the replies. I was thinking it might be a bad switch. I have disconnected the switch from a bad poe switch and plugged it directly into the firewall. It has been running for almost 2 hours with no issues so far. (Fingers Crossed)

[bholmes12]

@Mike_RappI have seen issues where the switch reports BAD DNS when the switch is getting an IP address outside of what the switch considers to be its management vlan. 

Do you have a specific MGT vlan and if so do you have the switch set to use that MGT VLAN? 

Switch > switch settings > vlan configuration

[Mike_Rapp]

I found that when I plugged it into the main switch, the switch port I plugged it into was set for another vlan thereby causing the issue, because when I plugged the switch directly into the firewall all issues seem to resolve. Thanks for the assistance.

[MRCUR]

@bholmes12 Ah yes, I didn't even think of that. Much like we say "It's always DNS", perhaps for MS issues we should say "It's always the MGMT VLAN". 

If anyone from the MS team is reading this, I'd say in general that the switches don't respond very well to not being in their defined management VLAN. Sometimes I just need to get a switch online in the "wrong" VLAN - I just wish they would behave a bit better when this happens. 

[BHC_RESORTS]

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@MRCUR wrote:

@bholmes12 Ah yes, I didn't even think of that. Much like we say "It's always DNS", perhaps for MS issues we should say "It's always the MGMT VLAN". 

If anyone from the MS team is reading this, I'd say in general that the switches don't respond very well to not being in their defined management VLAN. Sometimes I just need to get a switch online in the "wrong" VLAN - I just wish they would behave a bit better when this happens. 

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I've noticed this as well. A fallback/failover config for when this happens would be useful. I'm not a huge Cisco network guy, but I know some other vendors have this feature and it has saved me before when my config didn't work quite the way I wanted it.