Re: [tlug] Re: Absurd DNS failures.

[Michael Doughty <tlug@example.com>]

On Fri, Jul 04, 2003 at 09:08:28AM +0900, terranova@example.com wrote:
> 
> There could be. First up, there's nothing 'automatic' about it, as I'm 
> sure you realize. Do you know about /etc/resolv.conf? This is where 
> nslookup and other Lx/Ux progs will look for nameserver IP's. Your 
> ISP's nameserver IP's should be in here, but I'm not aware of anything 
> in Lx that does this 'automatically'. 

A properly functioning DHCP script will populate /etc/resolv.conf with the 
proper name servers provided your DHCP provides them in its response.  If
it doesn't, fix it.  ;)
 
> Let's assume that they are, but that your ISP's DNS setup is faulty, and doesn't have links through to other nameservers. If this is the case, it will succeed with 'local' domain names, but fail with wide area ones.

Err, hit return every 70 characters or so please.

> On the other hand, M$ OS's 'know about' M$'s site, probably including its nameservers, and undoubtedly fall back to them in the event of trouble. This could explain why the M$ dialin succeeds where the Lx one fails.

Are you suggesting that M$ hardcoded the IP addresses of their own 
nameservers into their operating systems?  I mean, it is MS, so anything
is possible, but that seems ludicrous even for them.
 
> > Back to Linux, and something that I only reproduced twice in one day because
> > this was enough to persuade me that this is unbelievable.
> > "nslookup www.asia.microsoft.com" found CNAME records for microsoft.com
> > and listed several addresses starting with 207.46.
> > But "nslookup microsoft.com" timed out and said it could not reach any name
> > servers.
> 
> This tends to confirm my doubts about your ISP's DNS setup.

Actually, if you dig @ the nameservers he provided, microsoft.com comes
back in a flash.  No problems.  I got six answers from both in an average
of about 165msec each.  The nameservers are fine, at least in general.

Now, for the reason I actually bothered to post, I have had similar issues
with responses from certain sites(Apple's Sherlock, google.com, yahoo.com) 
with my internet connection.  

Turned out that my problem was I was going through a LinkSys firewall/
router thing that was causing weird issues.  If I bypassed the linksys 
device everything was golden.  And sometimes, everything worked fine 
even with the LinkSys device in the loop, but other times google.com, 
yahoo.com, and a few other sites were simply inaccessible.  

I scoured the web but couldn't find any references from 
anyone else having this issue.  If this were just the result of the 
linksys device, I should have found a large number of reports.  This 
leads me to believe Jens SpinNet has something slightly odd with their 
infrastructure.  

Michael hasn't thought of a good way of identifying the problem.