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D-Link VPN Router => DSR-250N => Topic started by: jsch on January 08, 2013, 01:44:12 AM

Title: DSR-250N - DNS Lookup failure
Post by: jsch on January 08, 2013, 01:44:12 AM
Hi,

From time to time my browsers fails DNS lookup, so I get an error page. When reloading the page there is no problem.

The DSR-250N is configured as simple as possible; Vlan disabled, IPS disabled, IPv6 disabled, proxy disabled etc.

Firmware Version: 1.05B53_WW - Hardware Version: A1

I'm using OpenDNS and I never had any problems.

Any suggestions to how I can find out more to this problem.


Title: Re: DSR-250N - DNS Lookup failure
Post by: FurryNutz on January 10, 2013, 07:20:34 AM
Link>Welcome! (http://forums.dlink.com/index.php?topic=41537.0)

What region are you located?
Are you wired or wireless connected to the router?
Has a Factory Reset been performed?

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 (http://www.practicallynetworked.com/networking/fixing_double_nat.htm)
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.
Test by using default DNS options and default DNS that comes from the ISP to see if you get the same condition.

Setup DHCP reserved IP addresses for all devices ON the router. 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.

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.

Set current Time Zone, Date and Time. Use an NTP server feature.
 
Title: Re: DSR-250N - DNS Lookup failure
Post by: jsch on January 15, 2013, 01:25:39 AM
Hi FurryNutz,

Thanks a lot for your answer, much appreciated.

For the past week I haven't had any problems.
My ISP did replace some hardware and maybe that caused some routing problems.

Also I did some changes to the configuration, as you have suggested.

I the next couple of days I will test the router with the proxy options enabled, (Setup->Network settings->LAN setup config->Enable DNS Proxy) so I can use the  "DNS Host Name Mapping" feature.
I hope this works, one of the reasons I chose this router.

I hope you might can answer me this;
In "Advanced -> Firewall Settings -> ALGs -> Enable ALGs" there is an option to enable DNS.
I can't quite figure out the meaning of this DNS option.

The help says:
DNS: Allows NAT-PT (Network Address Translation/Protocol Translation) implementations to meet DNS address mapping requirements.

Should this be enabled of disabled?

Title: Re: DSR-250N - DNS Lookup failure
Post by: FurryNutz on January 15, 2013, 07:04:30 AM
I would say if it's off by default, leave it off. You can test it to see if it makes any difference. Thats a new option to me so I don't have much info on it. Is there anything in the User Manual about it? I would presume if your not using any kind of DNS mappings in that regard, it might not be needed. Let us know what happens if you enabled it.
Title: Re: DSR-250N - DNS Lookup failure
Post by: Gatorpan on July 25, 2013, 11:48:16 PM
I was having DNS issues on my network. Bascially, slow response, when I measured this with Gibson Research tool, the DNS worked fine. But users had frequently to click 2x to get a web site. I enabled the ALG and DNS. This seems to have solved the problem.

HW: A1, FW: 1.05B91_WW

If anybody has other recomendations I would like to know.
Title: Re: DSR-250N - DNS Lookup failure
Post by: FurryNutz on July 26, 2013, 07:02:28 AM
Thank you for sharing. Glad you got it fixed. Enjoy.

I was having DNS issues on my network. Bascially, slow response, when I measured this with Gibson Research tool, the DNS worked fine. But users had frequently to click 2x to get a web site. I enabled the ALG and DNS. This seems to have solved the problem.

HW: A1, FW: 1.05B91_WW

If anybody has other recomendations I would like to know.
Title: Re: DSR-250N - DNS Lookup failure
Post by: NetModem on February 18, 2015, 07:13:47 PM
I know I'm late on this issue but since its still an issue with these devices even with the latest hardware and firmware I figured I will respond with the fix. I was having this problem as well whenever I used DNS servers other than the ones provided by my router via my ISP. The fix was to uncheck the "Block UDP flood" option under Advanced -> Advanced Network -> Attack Checks.

You could also leave this option enabled and just raise the "UDP Connnection Limit" value but since I did not know a proper value for this, I just disabled it since all it does is make sure a UDP flood does not come from inside my network/LAN. I played around with setting this value to around 160 (found on MSDN) and it also solved the problem. Since DNS utilizes UDP, I am assuming the router was blocking multiple DNS lookups from a single IP since browsers prefetch them many at a time.
Title: Re: DSR-250N - DNS Lookup failure (RESOLVED)
Post by: FurryNutz on February 19, 2015, 06:51:08 AM
Thank you for posing this information. Hope it will help future users in addition to the other information posted.

Enjoy. ;)

I know I'm late on this issue but since its still an issue with these devices even with the latest hardware and firmware I figured I will respond with the fix. I was having this problem as well whenever I used DNS servers other than the ones provided by my router via my ISP. The fix was to uncheck the "Block UDP flood" option under Advanced -> Advanced Network -> Attack Checks.

You could also leave this option enabled and just raise the "UDP Connnection Limit" value but since I did not know a proper value for this, I just disabled it since all it does is make sure a UDP flood does not come from inside my network/LAN. I played around with setting this value to around 160 (found on MSDN) and it also solved the problem. Since DNS utilizes UDP, I am assuming the router was blocking multiple DNS lookups from a single IP since browsers prefetch them many at a time.
Title: Re: DSR-250N - DNS Lookup failure
Post by: uhu on February 19, 2015, 10:05:25 AM
...Since DNS utilizes UDP, I am assuming the router was blocking multiple DNS lookups from a single IP since browsers prefetch them many at a time.

Sounds logical.  Great info. Thanks.
Title: Re: DSR-250N - DNS Lookup failure
Post by: FurryNutz on February 19, 2015, 10:07:54 AM
Let us know if it helps you out.
Title: Re: DSR-250N - DNS Lookup failure
Post by: IanSmith on September 04, 2015, 09:24:39 AM
This fixed it for me. Thank you!

I was banging my head against the wall on this issue. Would never have thought to try this fix.
Title: Re: DSR-250N - DNS Lookup failure (RESOLVED)
Post by: FurryNutz on September 04, 2015, 10:18:21 AM
Glad it worked for you and thank you for letting us know the results. Hope it helps future users.

Enjoy. ;)

This fixed it for me. Thank you!

I was banging my head against the wall on this issue. Would never have thought to try this fix.
Title: Re: DSR-250N - DNS Lookup failure
Post by: nicksimoneau on February 26, 2016, 05:21:09 PM
Just wanna told you that you save my life !

I was pissed of by this problem and dont find any solution until I find this forum and I have just register to let you know you have help me !

Thanks !
Title: Re: DSR-250N - DNS Lookup failure (RESOLVED)
Post by: FurryNutz on March 02, 2016, 07:10:40 AM
Glad it helped you. Enjoy.  ;)