Intermittent DNS failures

[sbsnb]

Apologies again, I'm not reading you posts closely enough. Too many very similar filenames.

What's the output of:

cat /etc/resolv.conf

grep -i mypc /var/lib/misc/dnsmasq.leases

admin@RT-AX86U-AR28:/jffs/scripts# cat /etc/resolv.conf
nameserver 127.0.0.1

admin@RT-AX86U-AR28:/jffs/scripts# grep -i myPC /var/lib/misc/dnsmasq.leases
30089 f7:a4:67:4d:5f:8a 192.168.1.43 myPC 01:f7:a4:67:4d:5f:8a

 

[ColinTaylor]

Well I'm at a complete loss. Your dnsmasq setup is effectively identical to mine.

The only thing I can think of is to try adding an entry for myPC into the router's DHCP Server Manually Assigned list and see if it resolves then.

 

[sbsnb]

When I tried that it hung dnsmasq. All nslookups timeout until I disable manual assignment and remove the assignment in the UI.

 

[sbsnb]

Mar 27 08:55:00 dnsmasq[7103]: duplicate dhcp-host IP address 192.168.1.43 at line 61 of /etc/dnsmasq.conf
Mar 27 08:55:00 dnsmasq[7103]: FAILED to start up
Mar 27 08:55:28 dnsmasq[7220]: duplicate dhcp-host IP address 192.168.1.43 at line 61 of /etc/dnsmasq.conf
Mar 27 08:55:28 dnsmasq[7220]: FAILED to start up
Mar 27 08:55:58 dnsmasq[7364]: duplicate dhcp-host IP address 192.168.1.43 at line 61 of /etc/dnsmasq.conf
Mar 27 08:55:58 dnsmasq[7364]: FAILED to start up

 

[ColinTaylor]

Doh! OK temporarily comment out the myPC entry in dnsmasq.conf.add and try again.

 

[sbsnb]

Doh! OK temporarily comment out the myPC entry in dnsmasq.conf.add and try again.

No dice

The proper dhcp-host line is added to /etc/dnsmasq.conf, but resolution still fails from clients or console.

 

[RMerlin]

Try using the FQDN when doing a lookup.

 

[sbsnb]

Same thing: NXDOMAIN.

 

[sbsnb]

I'm going to try upgrading firmware or reset, whichever is necessary, but I'm keen to track it down before I do that. Seems like there might be some special edge case where this happens and I'd like to know what it is before I nuke it.

 

[sbsnb]

nslookup on the router's own name works.

$ nslookup RT-AX86U-AR28
Server:  RT-AX86U-AR28.foo.lan
Address:  192.168.1.1

Name:    RT-AX86U-AR28.foo.lan
Address:  192.168.1.1

So it seems that it's not local name resolution per se, but incorporating DHCP clients into the mix that has gone wrong somewhere.

 

[ColinTaylor]

Did you remove lines from your config in post #51? The error line in post #64 is not even close. If you didn't remove lines that might suggest your config file has non-visible corruption.

I would try temporarily disabling your dnsmasq.conf.add file and trying again. Note that you need to use the FQDN. I forgot that's something that's fixed in the current firmware.

mv /jffs/configs/dnsmasq.conf.add /jffs/configs/dnsmasq.conf.add.disabled
service restart_dnsmasq
nslookup mypc.foo.lan

 

[sbsnb]

admin@RT-AX86U-AR28:/jffs/configs# mv dnsmasq.conf.add dnsmasq.conf.old
admin@RT-AX86U-AR28:/jffs/configs# service restart_dnsmasq

Done.
admin@RT-AX86U-AR28:/jffs/configs# nslookup myPC.foo.lan
Server:    127.0.0.1
Address 1: 127.0.0.1 localhost.localdomain

nslookup: can't resolve 'myPC.foo.lan'

 

[ColinTaylor]

admin@RT-AX86U-AR28:/jffs/configs# mv dnsmasq.conf.add dnsmasq.conf.old
admin@RT-AX86U-AR28:/jffs/configs# service restart_dnsmasq

Done.
admin@RT-AX86U-AR28:/jffs/configs# nslookup myPC.foo.lan
Server:    127.0.0.1
Address 1: 127.0.0.1 localhost.localdomain

nslookup: can't resolve 'myPC.foo.lan'

OK

cd /etc
cat hosts

 

[sbsnb]

admin@RT-AX86U-AR28:/tmp/etc# cat hosts
127.0.0.1 localhost.localdomain localhost
192.168.1.1 RT-AX86U-AR28.foo.lan RT-AX86U-AR28
192.168.1.1 RT-AX86U-AR28.local
192.168.1.1 router.asus.com
192.168.1.1 www.asusnetwork.net
192.168.1.1 www.asusrouter.com

That explains why the router's host name works.

 

[ColinTaylor]

You should be seeing an entry for "mypc". So something's not right with the "manually assigned" DHCP entry. Is that still enabled?

Check that you haven't got a rogue /jffs/configs/hosts or /jffs/scripts/hosts.postconf

 

[sbsnb]

You should be seeing an entry for "mypc". So something's not right with the "manually assigned" DHCP entry. Is that still enabled?

Check that you haven't got a rogue /jffs/configs/hosts or /jffs/scripts/hosts.postconf

For some reason I'm not allowed to post ouput anymore

 

[sbsnb]

jquery is giving a 403 on post when I include my console output.

 

[sbsnb]

admin@RT-AX86U-AR28:/jffs/configs# grep -i 'F7:A4:67:4D:5F:8A' /etc/dnsmasq.conf - Pastebin.com

Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time.

pastebin.com

 

[ColinTaylor]

View attachment 40406
jquery is giving a 403 on post when I include my console output.

It's because you're not allowed to post text that contains "/etc" followed by "/hosts" (without a space). Just insert a space and we'll know what you mean.

admin@RT-AX86U-AR28:/jffs/configs# grep -i 'F7:A4:67:4D:5F:8A' /etc/dnsmasq.conf - Pastebin.com

Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time.

pastebin.com

I'm out of ideas. I would now just factory reset the router and start gain.

 

[sbsnb]

I'm out of ideas. I would now just factory reset the router and start gain.

That's the plan. I was just hoping to debug it before I do. I always hate to waste an opportunity to track down a bug (if it's a bug). It would be neat if there was an easy way to emulate the router environment so I could keep an image of the router as it is now and play with it in a virtual environment.