dns issue?

Cherney John-CJC030 John.Cherney at motorola.com
Tue Jun 17 04:46:27 UTC 2008

No, it doesn't necessarily sound like DNS. Does nslookup of the hostname
return the right IP address (or at least the same IP address on both
your laptop and your original computer? Are ping and tracrt of the
hostname working?

This reminds me of a problem I ran into before. What are the IP
addresses of your laptop and computer? (Go to www.myipaddress.com. My
ISP had given me an IP address that had a last octet of 255. It wasn't a
/24 subnet, so it was a valid IP Address. It wasn't the broadcast
address that some routers thought it was. However, because of that
address, I wasn't able to hit the server at work, but I was able to hit
a server on the ISP for my work. The ISP routers were configured better
than the work routers. Once I got a different, non-255 IP address, I was
able to hit my work server and a whole bunch of other sites that I
thought were down. 

That may not be your problem at all, but I figure I might as well offer
that up, on the off chance that it helps. 

Good luck!

-----Original Message-----
From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
Behalf Of Kevin Darcy
Sent: Monday, June 16, 2008 8:57 PM
To: comp-protocols-dns-bind at isc.org
Subject: Re: dns issue?

warth33 at hotmail.com wrote:
> Well, I dont know if Im at the right place to post. If not, I hope 
> someone can tell me where to post this.
> There is a domain, domain.com. And then there is domain2.com. Both 
> share the same ip address. Everything seems to work allright.
> A couple of times, a fellow tells me that he cannot reach the page. He

> gets a "Page cannot be displayed". I contacted the support for the 
> dedicated server. Dont think they solved it. But at some time my 
> friend could view the page. Now, something more concrete.
> Yestareday, from my computer that is on a router, I viewed the page, 
> almost all the day. In the evening, when I typed the url, I got a 
> "Page cannot be displayed".
> I then opened my laptop (that is not connected to the router, and has 
> his own ip address) and browsed to domain1.com. I could see the page 
> from there.
> I got back to the pther computer, but I could still not see the page.
> Late in the evening, after I contacted the support (that only keeps 
> saying that they can view the page and that there are no issues on the

> server end) I could visualize the page again. Wow!
> Late in the night, again the same problem. NB: at the same time I 
> could view the page from my laptop. Actually i always can see the page

> from my laptop.
> Today, fro all the day, I have not been able to view tha page. Never.
> NB that domain2.com has almost always been reachable from computer 1.
> The support dont seems to care. "It is not a server end problem, we 
> cannot do anything about this. The only thing you can do is to contact

> your isp".
> So my question is: what happens with all thise people (because there 
> are other, Im not the only one. Not many, but I know that there are) 
> that will not reach the page? They will type the url, for the first 
> time. They will see a page cannot be displayed. And they will never 
> come back again.
> otherwise, according to the advice I got from the support, I can 
> contact my isp and, probably, all the isp in the world and tell them 
> that there is/can be some issue with my domain.
> is this posible? im not much for sysadmin, but I cannot believe this 
> is true. What do you think? Is this a normal situation? I think this 
> is unacceptable. Is there anyone that can give me an advice on how to 
> try to solve this?
Before you even consider DNS as a possible cause of this problem, you
should clarify exactly what kind of error your browser is getting. Is it
a 404 error? That means you talked to the server, but the specific URL
could not be accessed (e.g. someone deleted the web page). Is it a 403
error? That's authentication failure, and also indicates that you talked
to the web server but were not successful in retrieving the URL. Is it a
5xx-series error? That's a fatal error coming back from the web server. 
All of those errors excuse DNS, since you *did* actually talk to the web
server, and you wouldn't have been able to do that, presumably, if DNS
were screwed up.

(Caveats: I'm not a web expert, and the presence of a proxy may
complicate my descriptions above, since sometimes it will be the proxy
giving back the error response rather than the remote web server

Depending on your browser, DNS problems may or not be rather easy to
pick out. In the ancient version of Firefox I use for
testing/troubleshooting (v1.5), for instance, I get a "Bad Gateway ... 
[code=DNS_HOST_NOT_FOUND]" error if I try to go to a URL with a
non-existent domain name. Internet Explorer, on the other hand, is
rather hopeless in this regard, typically sending you off to a "search" 
page if something goes wrong with the DNS lookup, so, even if IE is your
"main" or "regular" browser, you may want to consider installing some
other browser if you want to do proper troubleshooting of these kinds of


                              - Kevin

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