Weird DNS behavior

SteveDallas · 07-25-2003, 10:15 AM

OK, so my little mini-review of buymusic.com was conducted from my office computer. I tried to look it up at home.. and couldn't get through.

Further investigation revealed that the domain buymusic.com was not being resolved over my DSL connection. I have tried several nameservers and they always come up with nothing returned. But, if I query the same nameservers from somewhere else (say, by ssh'ing to my mail serer at work and using nslookup there), all is happy with the same nameservers that failed from my home connection.

I don't think it's a problem wiht my computer (running winblows 98) because I duplicated the problem with my Red Hat 9 laptop, connected through the same DSL router (a DLink 604).

So it must be the router... or something in the DSL connection. Right?

I already tried resetting the router to factory settings. (I hadn't changed much but the admin password anyway.) Any other suggestions as to what might be causing this?

(And don't tell me it works for you, I know it works for you. I want to figure out why it doesn't work for ME.)

Undertoad · 07-25-2003, 10:35 AM

Is your provider blocking DNS and demanding you use *their* DNS services, maybe on another port?

Tobiasly · 07-25-2003, 11:17 AM

That would be my guess. They are doing what, when done to web connections anyway, is called a transparent proxy. They are blocking all outbound port 53 requests, and redirecting them to their own servers.

I'd definitely call and take them to task on this. If it doesn't say anything about this in your Terms of Service, they owe you an explanation.

juju · 07-25-2003, 12:48 PM

I have that same router, and have had the same problem. I fixed it by updating my firmware to version 2.18. Now it works fine!

There was some sort of technical reason for it that I didn't understand, like mangling packets or something.

(edit: convenient link)

SteveDallas · 07-25-2003, 06:55 PM

UT, I was using the ISP's (Verizon, but resold thru a mom&pop ISP) DNS servers as handed out by default thru PPPoE negotiation. I didn't start querying other servers till I was having trouble.

Thanks, juju, I will go for the upgrade, tho I'm still having trouble understanding why it would only affect certain domains (or even just one--I haven't noticed the problem with any other domain).

juju · 07-25-2003, 11:07 PM

Yeah, it was the same for me. The problem was a real bitch to diagnose, because it only happened on certain websites, but they were few and they were always the same sites every time. I just assumed for the longest time that various sites were just down. It was only when other people started telling me that they had been to the places I couldn't get to that I got suspicious.

Incidentally, you can see if your router really is your problem by just hooking your DSL modem directly into your computer. Just bypass the router and dial up directly. If it still doesn't work, it isn't the router.

SteveDallas · 07-26-2003, 08:27 AM

The upgrade did it; all is happy now. Thanks!!

I'm off to the scenic Pocono Mountains for a week of internet-less relaxation. Y'all be good and try not to burn the place down while I'm gone!

07-25-2003, 10:15 AM	#1
SteveDallas Your Bartender Join Date: Jan 2002 Location: Philly Burbs, PA Posts: 7,651	Weird DNS behavior OK, so my little mini-review of buymusic.com was conducted from my office computer. I tried to look it up at home.. and couldn't get through. Further investigation revealed that the domain buymusic.com was not being resolved over my DSL connection. I have tried several nameservers and they always come up with nothing returned. But, if I query the same nameservers from somewhere else (say, by ssh'ing to my mail serer at work and using nslookup there), all is happy with the same nameservers that failed from my home connection. I don't think it's a problem wiht my computer (running winblows 98) because I duplicated the problem with my Red Hat 9 laptop, connected through the same DSL router (a DLink 604). So it must be the router... or something in the DSL connection. Right? I already tried resetting the router to factory settings. (I hadn't changed much but the admin password anyway.) Any other suggestions as to what might be causing this? (And don't tell me it works for you, I know it works for you. I want to figure out why it doesn't work for ME.)

07-25-2003, 12:48 PM	#4
juju no one of consequence Join Date: Jun 2001 Location: Arkansas Posts: 2,839	I have that same router, and have had the same problem. I fixed it by updating my firmware to version 2.18. Now it works fine! There was some sort of technical reason for it that I didn't understand, like mangling packets or something. (edit: convenient link) Last edited by juju; 07-25-2003 at 12:51 PM.

07-25-2003, 10:35 AM	#2
Undertoad Radical Centrist Join Date: Jan 2001 Location: Cottage of Prussia Posts: 31,423	Is your provider blocking DNS and demanding you use their DNS services, maybe on another port?

07-25-2003, 11:17 AM	#3
Tobiasly hot Join Date: Mar 2002 Location: Jeffersonville, IN (near Louisville) Posts: 892	That would be my guess. They are doing what, when done to web connections anyway, is called a transparent proxy. They are blocking all outbound port 53 requests, and redirecting them to their own servers. I'd definitely call and take them to task on this. If it doesn't say anything about this in your Terms of Service, they owe you an explanation.

07-25-2003, 06:55 PM	#5
SteveDallas Your Bartender Join Date: Jan 2002 Location: Philly Burbs, PA Posts: 7,651	UT, I was using the ISP's (Verizon, but resold thru a mom&pop ISP) DNS servers as handed out by default thru PPPoE negotiation. I didn't start querying other servers till I was having trouble. Thanks, juju, I will go for the upgrade, tho I'm still having trouble understanding why it would only affect certain domains (or even just one--I haven't noticed the problem with any other domain).

07-25-2003, 11:07 PM	#6
juju no one of consequence Join Date: Jun 2001 Location: Arkansas Posts: 2,839	Yeah, it was the same for me. The problem was a real bitch to diagnose, because it only happened on certain websites, but they were few and they were always the same sites every time. I just assumed for the longest time that various sites were just down. It was only when other people started telling me that they had been to the places I couldn't get to that I got suspicious. Incidentally, you can see if your router really is your problem by just hooking your DSL modem directly into your computer. Just bypass the router and dial up directly. If it still doesn't work, it isn't the router.

07-26-2003, 08:27 AM	#7
SteveDallas Your Bartender Join Date: Jan 2002 Location: Philly Burbs, PA Posts: 7,651	The upgrade did it; all is happy now. Thanks!! I'm off to the scenic Pocono Mountains for a week of internet-less relaxation. Y'all be good and try not to burn the place down while I'm gone!

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