[Dnsmasq-discuss] How to troubleshoot NXDOMAIN for local devices?

[Andy Ruddock]

Todd Andrews wrote:
> Hi All,
> 
> I'm running dnsmasq 2.76 on a Raspberry Pi. It's been working great for
> months but today I started seeing an odd behavior for a specific local
> device and I don't know how to troubleshoot it.
> 
> The device is a Dell Inspiron 5577 Windows 10 Home edition laptop with the
> latest Windows updates. It's getting an IP address of 192.168.1.115. I
> first noticed the problem when I tried to establish a VNC connection to it
> because I can't connect via its hostname, "sagan", but I can connect via
> its IP address.
> 
> Neither the IP assignment nor the laptop's MAC address appear in
> dnsmasq.leases. The only reason I know it is assigned .115 is by physically
> going to the laptop and running the Windows 'ipconfig' program at the
> command prompt.
> 
> I've rebooted the Raspberry Pi and the Windows 10 laptop, but it hasn't
> made a difference.
> 
> More info below. Does anyone have any ideas?
> 
> Regards,
> Todd


Are you sure the windows box hasn't been configured with a static IP
address?

Any information when you refresh the IP address from within a cmd window
in Windows?
	ipconfig /renew

> 
> 
> 1. dnsmasq.log shows:
> 
> /var/log/dnsmasq.log:Feb 15 12:38:34 dnsmasq[738]: config 192.168.1.115 is
> NXDOMAIN
> 
> 
> 2. I believe the following are the relevant dnsmasq config file entries.
> These have been working for quite some time. I'm obfuscating the full MAC
> address:
> 
> dhcp-host=f4:8e:38:xx:xx:xx,sagan
> 
> 
> domain=si.loc
> local=/si.loc/
> expand-hosts
> 
> 
> 3.  $ dnsmasq --test
> 
> dnsmasq: syntax check OK.
> 
> 
> 4. Using the program WinIPConfig2012 a.k.a. WinIPConfig 4.0
> <http://www.pkostov.com/wordpress/?p=19>, I've verified that the laptop is
> using the Raspberry Pi as the DHCP server. There's no other DHCP server on
> my network that I know of.
> 
> 5. On a third computer, a Macintosh, I get these results. The Raspberry Pi
> is at 192.168.1.40.
> 
> $ ping sagan
> 
>       *ping: cannot resolve sagan: Unknown host*
> 
> $ ping sagan.si.loc
> 
>       *ping: cannot resolve sagan.si.loc: Unknown host*
> 
> $ dig sagan
> 
>      ; <<>> DiG 9.8.5-P1 <<>> sagan
>      ;; global options: +cmd
>      ;; Got answer:
>      ;; ->>HEADER<<- opcode: QUERY, status: *NOERROR*, id: 21157
>      ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
> 
>      ;; QUESTION SECTION:
>      ;sagan.                            IN      A
> 
>      ;; Query time: 1 msec
>      ;; SERVER: 192.168.1.40#53(192.168.1.40)
>      ;; WHEN: Thu Feb 15 13:22:25 PST 2018
>      ;; MSG SIZE  rcvd: 23
> 
> $ dig sagan.si.loc
> 
>      ; <<>> DiG 9.8.5-P1 <<>> sagan.si.loc
>      ;; global options: +cmd
>      ;; Got answer:
>      ;; ->>HEADER<<- opcode: QUERY, status: *NXDOMAIN*, id: 11132
>      ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
> 
>      ;; QUESTION SECTION:
>      ;sagan.si.loc.                     IN      A
> 
>      ;; Query time: 1 msec
>      ;; SERVER: 192.168.1.40#53(192.168.1.40)
>      ;; WHEN: Thu Feb 15 13:22:26 PST 2018
>      ;; MSG SIZE  rcvd: 30
> 
> $ nslookup sagan
> 
>      Server:            192.168.1.40
>      Address:   192.168.1.40#53
> 
>      Non-authoritative answer:
>      *** *Can't find sagan: No answer*
> 
> $ nslookup sagan.si.loc
> 
>      Server:            192.168.1.40
>      Address:   192.168.1.40#53
> 
>      ** *server can't find sagan.si.loc: NXDOMAIN*
> 
> 
> 
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> 


-- 
Andy Ruddock
------------
andy.ruddock at rainydayz.org (OpenPGP Key ID 0xB0324245)

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