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Author Topic: DIR-645 unable to resolve names via DNS (DNS is working OK on internal network)  (Read 42423 times)

ambercap

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My new DIR-645 is connected to a cable modem (WAN) and configured to use L2TP (dynamic).
The DNS fields are left blank.
On the status page I see the 2 DNS server IPs obtained via DHCP from the ISP.
DNS relay is enabled.
LAN IP is set to 192.168.2.1.

Local clients using DHCP get 192.168.2.1 as the default gateway as well as the DNS server.
All local machines (LAN and WiFi) have no problem resolving names via DNS (relayed by the router to the external servers) and everything works great.

The problem is the router itself is unable to resolve any names whatsoever. If I enter the web UI the following features therefore do not work:
  Can't use a host name for the ISP gateway for L2TP - I'm using the IP instead.
  Can't use a host name for the SMTP gateway for emailing the router log files - using the IP instead.
  On the system check page (ping) I can't ping for example www.google.com - pinging the actual IP succeeds.
  I can't get NTP to work to set the router's time as it can't resolve ntp1.dlink.com and since this is a dropdown list, I can't type in another host nor the IP.
  I can't check for f/w updates via the web UI (not that I need to).
  I can't update DDNS as it can't resolve dlinkddns.com

I suspect this is because the router does not update its /etc/resolv.conf file (there is a message complaining about an empty resolv.conf in its log).

I tried entering the DNS IPs in the network settings page but it made no difference.

I was able to get NTP to work at least by saving the config.bin, extracting the xml, changing ntp1.dlink.com to the actual IP, repacking config.bin and restoring it. Now NTP works and I see the IP displayed (though the dropdown shows no NTP server selected).

I can't do the same for DDNS since there is no server entry in the config - just <provider>DLINK</provider>.

So at this point the most annoying problem is I can't use the DDNS feature due to the failure to resolve any names.

Any ideas? Is this just a f/w bug? Any way to fix it by fiddling with config.xml entries? eg. set <dns4> for WAN-1 to DNS4-1?
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FurryNutz

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Link>Welcome!
What Hardware version is your router? Look at sticker under router.
Link>What Firmware version is currently loaded? Found on routers web page under status.
What region are you located?

What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?

If this modem has a built in router, it's best to bridge the modem. Having 2 routers on the same line can cause connection problems.
Double NAT
To tell if the modem is bridged or not, look at the routers web page, Status/Device Info/Wan Section, if there is a 192.168.0.# address in the WAN IP address field, then the modem is not bridged.
If the modem can't be bridged then see if the modem has a DMZ option and input the IP address the router gets from the modem and put that into the modems DMZ.
Check ISP MTU requirements, Cable is usually 1500, DSL is around 1492 down to 1472. Call the ISP and ask.

Some things to try: - Log into the routers web page at 192.168.0.1. Use IE, Opera or FF to manage the router.
Turn off ALL QoS or Disable Traffic Shaping (DIR only) GameFuel (DGL only and if ON.) options. Advanced/QoS or Gamefuel.
Turn off Advanced DNS Services if you have this option under Setup/Internet/Manual.
Turn OFF DNS Relay under Setup/Networking and manually enter in DNS addresses from the ISP under Setup/Internet/Manual?
Setup DHCP reserved IP addresses for all devices ON the router. Setup/Networking. This ensures each devices gets its own IP address when turned on and connected, eliminates IP address conflicts and helps in troubleshooting.
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP under Advanced/Firewall.
Enable uPnP and Multi-cast Streaming under Advanced/Networking. Disable uPnP for testing Port Forwarding rules.
WAN Port Speed set to Auto or specific speed? Some newer ISP modems support 1000Mb so manually setting to Gb speeds can be supported by the router. Advanced/Advanced Networking/WAN Port Speed
Set current Time Zone, Date and Time. Use an NTP server feature. Tools/Time.
« Last Edit: January 15, 2013, 08:55:23 AM by FurryNutz »
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Hard Harry

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If you disable DNS relay, does the problem go away? What firmware are you running?

From what I have seen certain routers will have a problem with DNS requests internal to themselves. IE, if you query the NTP domain locally on the PC, it would work, but the router itself cant send the query.
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ambercap

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Just some more info:

My DIR-645 is h/w version A1.
I updated the f/w from 1.01 to 1.03 (the latest).

I'm in Israel and my WAN connection is via cable using a Motorola cable modem SBV5121 (no built-in router).
My ISP is Netvision connected via L2TP.
Since the modem has no router, my WAN IP is a public IP (217.132.....).

I am using the factory defaults for everything, except for configuring the bare minimum to obtain connectivity.

I did try disabling DNS relay and it made no difference.
I also tried entering the DNS servers under network settings.
However I don't think I tried entering the DNS servers and disabling DNS relay at the same time.

As I said, all devices on the router's LAN have no problem resolving hosts such as NTP and DDNS.
It is only the router itself that is unable to resolve any hosts.
I see many posts in various forums where NTP does not work for several models of DLink routers and it is my guess that this is a general bug with DLink routers where they are unable to resolve DNS entries.
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FurryNutz

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Just some more info:

My DIR-645 is h/w version A1.
I updated the f/w from 1.01 to 1.03 (the latest).

I'm in Israel and my WAN connection is via cable using a Motorola cable modem SBV5121 (no built-in router).
My ISP is Netvision connected via L2TP.
Since the modem has no router, my WAN IP is a public IP (217.132.....).

I am using the factory defaults for everything, except for configuring the bare minimum to obtain connectivity.

I did try disabling DNS relay and it made no difference.
I also tried entering the DNS servers under network settings.
However I don't think I tried entering the DNS servers and disabling DNS relay at the same time. <Can you try to disable DNS Relay and then enter in manual DNS addresses to see if this helps?

As I said, all devices on the router's LAN have no problem resolving hosts such as NTP and DDNS.
It is only the router itself that is unable to resolve any hosts.
I see many posts in various forums where NTP does not work for several models of DLink routers and it is my guess that this is a general bug with DLink routers where they are unable to resolve DNS entries. NTP services work on all the routers I've tested including this one. Possible this could be an ISP service issue instead. Have you tried a different NTP server?

Maybe someone can review your router settings with you using Link> teamviewer if your interested. Its safe and secure.
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ambercap

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OK I disabled DNS relay and copied the 2 DNS IPs from the status page to the Internet page, which restarted the L2TP connection. The router is still unable to resolve any hosts. This does not make any sense.

No NTP server choice will work since the router is unable to resolve ANY host. That is why I've forced the NTP host to be 61.67.210.241 which was what I got from a name lookup for ntp1.dlink.com:

> ntp1.dlink.com
Server:      192.168.2.1
Address:   192.168.2.1#53
Non-authoritative answer:
Name:   ntp1.dlink.com
Address: 61.67.210.241
Name:   ntp1.dlink.com
Address: 205.171.76.135

Which gives in the WUI:

The time has been successfully synchronized.
(NTP Server Used: 61.67.210.241, Time: 2013/01/16 17:59:40)
Next time synchronization: 2013/01/23 17:59:40

I doubt there is any setting I can change in the router - it seems like a router bug. If there was some way to ssh in I could see what is going on, but there isn't.

Since NTP works using the IP instead of hostname, that does not bother me any more.

More importantly, I wish I could get DDNS to work. It can't resolve dlinkddns.com to 216.146.38.125 so fails to update the outside IP.
« Last Edit: January 16, 2013, 08:19:59 AM by ambercap »
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FurryNutz

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After setting manual DNS and turning off DNS Relay, did you restart your PC or do a ipconfig /flushdns at the commend prompted before testing?

I need to dig up a thread that I think we had tested on this, either in here or in the 857 forum. I'll see if I can find it.  :-\
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ambercap

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What has the PC got to do with anything? I only need the PC to get into the router's WUI. I can completely disable DNS on the PC since it only needs to connect to 192.168.2.1. It is not the PC that has the DNS problem, it is the router itself! I have to assume that the router is not updating its own resolv.conf file and therefore gethostbyname is failing when called by services such as NTP, SMTP, DDNS, ping...
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FurryNutz

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One you make changes on the router regarding DNS, anything connected to the router will need to be either restarted or the DNS caches flushes to get the new settings.

How are you attempting to execute an resolution process? Can you give us an example? Are you using a command line shell or some program?

I recommend that you phone contact DLink support, level 2 or higher and inquired about this to see if they can help you get this going and identify where the problem lies.
« Last Edit: January 16, 2013, 09:27:18 AM by FurryNutz »
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ambercap

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I am not using any command line shell nor any program - you seem to be missing the point here. I am doing everything via the router's web UI (via FireFox). I browse to 192.168.2.1, then I click on the Tools tab and click on System Check and enter an address to ping (such as www.google.com). The router fails to ping the host since it is unable to resolve the IP.

Similarly for other router functions, such as emailing the router logs, updating dynamic DNS or time via NTP. It is the ROUTER that fails to resolve by DNS - NOT the PC!

Twice I emailed DLink support - no response.

I guess I will have to try phone them.
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FurryNutz

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Thats more helpful information.

Doe it resolve if you try the IP address instead or will it allow an IP address?> 74.125.225.105
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ambercap

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Yes if I try to ping an actual IP address from the router then the ping succeeds.
Similarly if I configure the SMTP server to email the router logs using an IP address instead of host name it succeeds.
If I force the NTP server to the actual IP it succeeds (as I already wrote earlier).

It is only DNS resolution that is failing (for the actual router).
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Hard Harry

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Yea, I have seen this before. I don't think its a problem with a certain series, because I have seen people with different Dlink routers, some have the issue, some don't. I just don't think it has ever been pinned down because its hard to completely rule out user error enough to isolate. You sound quite knowledgeable, maybe you can help?

Could you clear the logs, enable all options of logs, then reboot and post the results? I feel the error will show itself there. I doabt, as you say, you will be able to change anything in the UI to fix, but atleast then it will confirm the issue.
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FurryNutz

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I just ran a ping test from my DIR-655 v2.10NA FW from the Check Status menu and it reported the following:
Response from www.google.com received in 43 milliseconds. TTL = 49
Response from www.google.com received in 81 milliseconds. TTL = 49
Response from www.google.com received in 43 milliseconds. TTL = 49
Response from www.google.com received in 44 milliseconds. TTL = 49
User stopped
Pings sent: 6
Pings received: 5
Pings lost: 1 (16% loss)
Shortest ping time (in milliseconds): 43
Longest ping time (in milliseconds): 81
Average ping time (in milliseconds): 50

Also using the IP address worked too.
I'll put my 645 on-line tonight and check it as well.
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ambercap

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This is an excerpt from the logs - the very first line being the only indication of a problem (which I also mentioned earlier) (empty resolv.conf):

[System]
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
[Time]Wed Jan 16 12:58:27 2013
[Message:1]no servers found in /etc/resolv.conf, will retry
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:39 2013
[Message:2]DHCP: Client send DISCOVER.
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:39 2013
[Message:3]DHCP: Client receive OFFER from 172.18.144.176.
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:39 2013
[Message:4]DHCP: Client send REQUEST, Request IP 172.21.181.105 from 172.18.144.176.
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:39 2013
[Message:5]DHCP: Client receive ACK from 172.18.144.176, IP=172.21.181.105, Lease time=601976.
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:40 2013
[Message:6]pppd 2.4.2b3 started by (unknown), uid 0
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:7]PAP authentication succeeded.
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:8]IPCP: local IP address (217.132.254.65)
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:9]IPCP: remote IP address (212.143.205.233)
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:10]IPCP: primary DNS address (194.90.1.5)
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:11]IPCP: secondary DNS address (212.143.212.143)
--------------------------------------------------------------------------------------------
[Time]Wed Jan 16 12:58:41 2013
[Message:12]WAN connected [L2TP]
--------------------------------------------------------------------------------------------
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