[Dnsmasq-discuss] How to troubleshoot NXDOMAIN for local devices?
Todd A
taa at pobox.com
Fri Feb 16 17:03:02 GMT 2018
On Thu, Feb 15, 2018 at 2:46 PM, Andy Ruddock
<andy.ruddock at rainydayz.org <mailto:andy.ruddock at rainydayz.org>> wrote:
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
Hi Andy, thanks for getting back to me so quickly. (I originally sent
this reply yesterday but forgot there's a maximum size per post to this
list. Replaced screen capture with a link below.)
Are you sure the windows box hasn't been configured with a static IP
address?
I'm positive: click to view screen capture
<https://www.dropbox.com/s/cwy72yu4sly62mp/sagan-configured-as-dhcp.PNG?dl=0>
Any information when you refresh the IP address from within a cmd window
in Windows?
ipconfig /renew
I never would have thought to try this. It gave a strange error but
renewing fixed the problem immediately. Here's the error:
C:\Users\taa>ipconfig /renew
Windows IP Configuration
An error occurred while renewing interface Ethernet : The name
specified in the network control block (NCB) is in use on a remote
adapter.
The NCB is the data.
C:\Users\taa>
Having a specific error allowed me to Google it and find Bizarre DHCP
server error solved
<https://web.archive.org/web/20161126203756/http://www.formortals.com/bizarre-dhcp-server-error-solved/>.
The poster at that link 1) was not getting an IP address at all, 2) was
running a Windows DHCP server, and 3) "found a second reservation in
DHCP which looked odd; it had the same IP address as the first one that
we deleted but it had an entirely different MAC and name."
This made me remember that a couple of weeks ago I changed my laptop's
Computer Name in Windows.
Does this mean there is some other place where dnsmasq might have cached
the IP address or MAC or hostname? I'm trying to figure out
why dnsmasq.leases had no reference to the laptop's IP/MAC/hostname,
neither the previous hostname or the new one. Maybe this is one of those
cases that is so bizarre it defies explanation (and I can live with
that). :D
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