Unable to get local DNS resolution to work

Chezdude

New Around Here
I've searched in the forums and followed the posts I could find on getting local DNS resolution for DHCP reservations to work, but I'm just missing something. I've tried all sorts of setting changes, and no difference.

Setup: AsusWRT-Merlin 380.57 running on an RT-N66U
Local DHCP server is enabled
Range is .100-.149 (not all the reservations are in this range, if that matters)
Domain Name is blank (I've tried various values, it didn't make a difference)
DNS Server 1 and 2 are both blank (I'm overriding the WAN DNS on that page to use OpenDNS)
Advertise routers IP in addition to is checked
Forward is no
DNSSEC is no
And all my local addresses are set under the manual assignment

I SSH into the router and have verified the /etc/dnsmasq.conf and associated files all look correct.

But when I do nslookup from a computer on the network to the router, I get Not Found results.

Code:
MegaMac:~ heath$ host mythtv-backend
Host mythtv-backend not found: 3(NXDOMAIN)
MegaMac:~ heath$ nslookup mythtv-backend
Server:        192.168.2.1
Address:    192.168.2.1#53
** server can't find mythtv-backend: NXDOMAIN

So the local DNS server is running, it's just not actually using the manual values.

/etc/dnsmasq.conf
Code:
pid-file=/var/run/dnsmasq.pid
user=nobody
bind-dynamic
interface=br0
interface=ppp1*
no-dhcp-interface=ppp1*
resolv-file=/tmp/resolv.conf
servers-file=/tmp/resolv.dnsmasq
no-poll
no-negcache
cache-size=1500
min-port=4096
dhcp-range=lan,192.168.2.100,192.168.2.149,255.255.255.0,86400s
dhcp-option=lan,3,192.168.2.1
dhcp-option=lan,44,192.168.2.250
dhcp-option=lan,252,"\n"
dhcp-authoritative
read-ethers
addn-hosts=/etc/hosts.dnsmasq
interface=tun21

/etc/hosts.dnsmasq
Code:
192.168.2.197 Anna-ipod
192.168.2.139 mythtv-backend
192.168.2.10 mightymac

/tmp/resolv.conf
Code:
[email protected]:/tmp/home/root# more /tmp/resolv.conf 
nameserver 208.67.222.222
nameserver 208.67.220.220

/tmp/resolv.dnsmasq
Code:
[email protected]:/tmp/home/root# more /tmp/resolv.dnsmasq

I had all this working great on Tomato Shibby on an old Linksys e2000, but I can't seem to recreate that setup on the Asus. I know that it's possible as I've seem forum posts from others, so I must just be missing something.

Also, how can I enter a manual value for the router itself? In Tomato, you would enter a value with no MAC address. But AsusWRT won't allow that. It also won't allow multiple MAC address for the same hostname (useful if you have a system that connects to the network multiple ways, like wired and wireless).

Thanks,
chezdude
 

Chezdude

New Around Here
Ok, I found the problem. I had enabled the DNS Filtering option (since I do use OpenDNS). Apparently, that causes the internal DNS server to not respond to local requests. As soon as I turned that off, local resolution started to work just fine.

I am still overriding the WAN DNS with the OpenDNS IPs, but I think I need to find some docs on the DNS filtering option. I had it enabled, set it to OpenDNS Home, but has the list blank thinking that it would apply to any client.

Should I be able to use local DNS resolution in addition to the DNS filtering? Or is it an exclusive OR?

I can't see any differences in the dnsmasq config files. How does the DNS filtering actually work?

Thanks,
chezdude
 

RMerlin

Asuswrt-Merlin dev
Ok, I found the problem. I had enabled the DNS Filtering option (since I do use OpenDNS). Apparently, that causes the internal DNS server to not respond to local requests. As soon as I turned that off, local resolution started to work just fine.

I am still overriding the WAN DNS with the OpenDNS IPs, but I think I need to find some docs on the DNS filtering option. I had it enabled, set it to OpenDNS Home, but has the list blank thinking that it would apply to any client.

Should I be able to use local DNS resolution in addition to the DNS filtering? Or is it an exclusive OR?

I can't see any differences in the dnsmasq config files. How does the DNS filtering actually work?

Thanks,
chezdude

DNSFilter causes all DNS requests to be sent to the specified DNS, so your local dnsmasq never gets a chance to try to resolve them.

For your particular scenario, you'll want to override the DNS servers on the WAN page instead.
 

busch09

Regular Contributor
Hmm, just noticed I have the same issue. I have 3 Asus running (3100,68,66) all with merlin 380.68_2. 3100 is hooked up to WAN, 68 and 66 as AP with Ethernet cable.

I can ping/nslookup the router by hostname, but no other devicesneither the AP routers nor any other device on my network. ping by ip works on all of them. Please find my screen attached.

Code:
HTMAC-139:~ hdtv$ ping ac3100
PING ac3100.home.test (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: icmp_seq=0 ttl=64 time=1.906 ms

HTMAC-139:~ hdtv$ nslookup ac3100
Server: 2601:646:c600:1f13::1
Address: 2601:646:c600:1f13::1#53
Name: ac3100.home.test
Address: 192.168.1.1
But no other devices on my network:
Code:
HTMAC-139:~ hdtv$ ping ac66
ping: cannot resolve ac66: Unknown host

HTMAC-139:~ hdtv$ nslookup ac68
Server: 2601:646:c600:1f13::1
Address: 2601:646:c600:1f13::1#53
** server can't find ac68: NXDOMAIN
Screen Shot 2017-09-23 at 1.23.31 PM.png
Screen Shot 2017-09-23 at 1.22.21 PM.png
Screen Shot 2017-09-23 at 1.22.03 PM.png
Screen Shot 2017-09-23 at 1.21.54 PM.png
 
Last edited:

Jack Yaz

Part of the Furniture
DNS SERVER 1 and WINS Server should be blank
 

ColinTaylor

Part of the Furniture
@busch09 Your problem doesn't sound like the OP, which was caused by DNS Filtering being enabled.

You need to tell us how your AC66 and AC68 are configured and connected to the AC3100. Are they configured as routers with their own subnet or are they access points?

Also, you say can ping/nslookup "no other devices". Do you really mean all devices on your LAN or just those two routers?
 

busch09

Regular Contributor
@busch09 Your problem doesn't sound like the OP, which was caused by DNS Filtering being enabled.

You need to tell us how your AC66 and AC68 are configured and connected to the AC3100. Are they configured as routers with their own subnet or are they access points?

Also, you say can ping/nslookup "no other devices". Do you really mean all devices on your LAN or just those two routers?

Edited original post with answers to @ColinTaylor questions.
 

Attachments

  • Screen Shot 2017-09-23 at 1.29.30 PM.png
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ColinTaylor

Part of the Furniture
You won't be able to resolve the access point names because they don't register their names in DNS the same way Windows PC's do (for example).

If you create a DHCP reservation on the AC3100 for each access point you can specify their host names there and they will be added to DNS.

You should already be able to do name resolution for any Windows DHCP clients on your LAN.
 

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