dsnmasq cname infor lost after reboot

[Patrick9876]

The subject of the post is very poorly worded.

I have a dnsmasq.conf.add file with a couple cname records adding host names to a NAS. After a reboot of the router the router's DSN does not know about these cnames. I have to disconnect and reconnect the NAS Ethernet cable in order for the DSN to get those cnames. I assume the disconnection and reconnection of the NAS cable prompts DHCP to give the NAS it's IP address and that somehow prompt the router's DSN to become aware of the cnames.

Note that all connectivity in the network is fine after the reboot. I can get to the NAS using its real host name with no problem. It's just those cnames that are unknowm.

Is there some way to get the router to automatically do whatever DNS magic is needed without the reconnection of the NAS? I don't always remember that step until I notice a bunch of connection failures because of unknown names in the DSN.

I currently have an AX86u running 3004.388.10 but this has been happening over the years with at least 2 routers and many releases. I assume this is intended behavior, but it's very inconvenient.

 

[ColinTaylor]

Is the NAS connected directly to the router via ethernet, or is it going via an intermediate switch?

Is the NAS's network interface configured as a DHCP client or is it manually configured? (I'm assuming you already have a DHCP reservation on the router)


EDIT: Déjà vu

This appears to be the same problem you reported here:

Dnsmasq peculiarity (maybe?)

RT-AC86U Merlin 384.18 Yesterday I was getting some dropped wireless connections so I rebooted my router (for the 1st time in over a month). After the reboot all powered up devices - 2 computers, 3 NAS devices, 1 thermostat on a guest network - showed in the router's client list except for 1...

www.snbforums.com

and here:

[AC86U, Merlin 384.14_2] Add CNAME to DNS server

I need to change the host name of a NAS drive because I used an "invalid" character in it's name. (Nothing in my network seems to care except a QNAP NAS that accepts only regerously conforming DNS names. So I need to change DS281_1 to DS218-1 if I want my QNAP NAS to talk with my Synology...

www.snbforums.com

 

[Patrick9876]

Yup. Same problem. I forgot I reported it back then.

My connection is now going through a switch. (It apparently was not back when I first reported this.)

The NAS gets its address via DHCP. And there is no problem accessing it with its address or actual host name after the reboot. It's just the CNAMEs that are unknown on the LAN.

Back in one of those threads you said

That's my point, the host name (and therefore an IP address, although that's irrelevant for our purposes) must be set on the router not just the NAS. The reason being, as you have seen before, is that there seems to be an issue with the NAS where it doesn't always register its name with the DNS server when it should. When this happens the name resolution will fail. The solution is to either fix the errant behaviour of the NAS, or work around the problem by setting the host name on the router.

But as near as I can see the NAS always does register it's name with the DNS server. It's just the additional CNAMEs that don't get registered.

Or maybe I'm wrong. The router's DHCP has been giving the NAS the same address since the router was installed and configured so it is obviously saving the name/address combination (indexed by the NAS MAC address, maybe?). Maybe the DHCP handshake is not actually happening when the router is booted and DHCP does it's initial processing. So you could be right about errant behavior in the NAS. (Sorry I didn't reason that out when you first said that 5 years ago.)

Do you know where I can find a good description of DHCP data flow when a DHCP server first starts up?

 

[ColinTaylor]

I'll have to test the CNAME behaviour again to see if it's changed over the last 5 years.

EDIT:
OK I've tested this again and the previous solution should still work. Or at least it does on my router.

 

[ColinTaylor]

Can you post the contents of your /etc/dnsmasq.conf file please.

 

[bennor]

I have a dnsmasq.conf.add file with a couple cname records adding host names to a NAS.

For context, might help if you post the dnsmasq.conf.add file.