Really weird internet/LAN problem - Help needed

Does this make any sense to anyone - all suggestions wellcome...

Out of the blue I got serious problems with my cable connection, which was (then) through a linksys router and static IP's on my home LAN running XP as the OS on the two internet connected PC's. So I switched to DHCP and plugged the cable modem directly into my main PC, but the problem stays the same. The cable company guys swear everything is in order in their end and claim that something is blocking traffic on my end. I reverted to a month old backup, switched the cable modem - but still face the same same problem.

The problem is that I cannot reach certain websites. They just refuse to display (with IE6) while most sites work OK. To make it even stranger, I can't even ping some of the sites, whereas others ping just fine, but the sites are not necessarily the same. For example; I cannot ping ntcompatibe, but I can view it alright in IE (sometimes some sideframes don't display though). On the other hand, I can both ping and view yahoo.com. Microsoft.com I can neither ping or view, BBC shows up just perfectly everytime.

I had zonealarm installed when this sh1t started, but it's now uninstalled and every reference to it deleted from the registry. Everything had worked just fine for months before.

Where the h-ll should I look for the problem ? Or, as I tend to believe, how can I find evidence for the cable guys that the problem is not on my end ?

H.

Sounds more like a DNS issue than anything else. Have you tried using another DNS server temporarily to see what happens? When pinging MS, do you resolve to an IP, only to not reach it or just not get an IP at all?

Here's one to try out:
207.170.3.6

Some sites you will never be able to ping. This is simply because they are blocking ICMP. I am not sure if this is true for NTCompatible's case but it's highley likely because I have never been able to ping their DNS or their IP.

Blocking ICMP is a good idea for security. Makes the newbies think they cannot connect to a site.

While connected to your ISP perform an IPCONFIG /ALL
There should be Primary and Secondary DNS servers. Try changing Primary DNS the Secondary and making your Secondary the Primary.(If your using DHCP this is fine you can still assign the DNS yourself).

Also contact your ISP and verify all settings with them.

Thanks for the suggestions.


Good idea, No, I haven't tried but will do as soon as I get home to the system again.


It normally resolves the IP allright (ie returns the numeric value) but then just gives me the timed out message. Some (most?) of the sites I can't reach are unresolved, no IP is reported back. The cable guys claim that they would have tons of complaints if the problem was with them.

Is there any file where XP or IE6 is storing DNS or IP addresses except in the registry ?

H.

If the system isn't being rebooted, and you want to delete all the resolved entries from the DNS table, then use "ipconfig /flushdns" from the command line and that will do the trick. Then, you can try hitting sites again without the need for a reboot to clear the table.

Also, check the network config in IE to see if some sort of proxy config was setup by accident.

This is some nightmare...

I've tried both DosFreaks suggestion to switch around primary and secondary DNS server and
Clutch suggestion to use a different one- with no luck.

I also tried to flush back to a fresh XP install (Drive Image) with not much else than XP installed. Same problem, only difference was that now I was able to ping the damned sites that I cannot connect to. It was slow, but the ping worked - but with IE6 not a chance.

The oddest thing is that I can't connect to My ISP's (the cable company) news server, and only randomly to their web page. When connecting to their newsserver I get an error 11004 which I believe means that some software is blocking. But there is none...

Somehow I can't imagine that the problem is on my end. About the same time this started the cable company switched DNS server adresses and as I was then accessing over a static IP thru a router it took a while to figure out. Now they maintain that I "must have something blocking traffic". Shoot, in order to get the butt moving at my cable company & ISP I need some strong proof that the problem is on their side. If it really is on my side I have no idea what to try out anymore or where it could be anyone have ideas on how to get forward ??

H.

Hmmm, Do you know of anyone else in your area with the same provider? Preferablly someone in the neighborhood....

You already checked your IP config's.
You checked your router.
You checked your computer.

Gotta be either them or something in-between.

Try using SamSpade to trace to your computer: http://www.samspade.org/

Then test your connectivity to the route-s in-between your IP and your ISP's.

SamSpade only traces my IP as "probable bogus rDNS: No DNS", I guess my ISp has some shields as my IP is a dynamic IP. Spade gets the canonical name right though.

H.

What's the connectivity to your DNS/Gateway Ip's like? Any timeout's?

It's OK, haven't seen any problems there. Timeouts rarely occure.
I'm getting toys in the attic though if I can't find the error or a way to convince the dark side that its their fault.

On a lighter side, the cable company sent over a guy three times to measure the signal strenght which they claimed was the cause of all this. They only gave up when I asked them to explain why certain websites have weaker signals than others and which strenght a site should be broadcasting with.

H.

Harry, you wouldn't by any chance be in the UK & using NTL for your ISP would you?

No, I'm not but thats of little comfort...
But if you have an idea on how to solve my problem please share it.

H.

I had something similar happen recently. It was a prob @ their end. I was able to prove it by running traces with NeoTrace, which showed that the trace was getting past hop #2 [hop 1 is my PC, hop 2 is the cable modem, #3 is the local DNS server]. If the trace gets past hop 2, but fails whilst still inside the ISP's network, then AFAIK the only possible explanation is it being the ISP's faul

I don't use Cable but I have DSL and your story sounds exactly what I have been going through for the last two months fighting with my ISP insisting the problems was not at my end. Finally yesterday a Techie showed up and did more than just change the modem but he ran some tests on the line and it turns out that my line was not grounded properly.So he had to climb a few poles (at over 100F God bless him!)
and properly grounded the wire and all has been much better since then.
Now I also know that years ago we were having problems with our cable (just for TV) and the techie who came did the same thing. he grounded the cable wire.. It was like a little splitter with a ground wire coming out of it but I don't know where you can get them.
Maybe that is your problems as well.
but the problems you are describing are an exact carbon copy of the ones I was having despite the fact I have DSL and you have Cable.
Hope this helps..
S

Geezus... Seems like everyone nowadays has a Linksys Router and a Microsoft Certification, including me. lol What the hell is going on???

Yeh people turning off ICMP do to DoS attacks makes finding net problems hard. Ping is a good general tool to check DNS and connectivety but trace route is much better to use on this case. Do not forget that if you find something funny on your ISP side then redirect the output to a file. I think the first thing I would do it just plug your cable modem into one of your machines. This will take out the possibility of the router. Not to mention your ISP will not have any reason to say it is on your end. Remember, anything more then cable to modem to machine then the ISP is automaticly going to say it is one your end unless it is a major obvous problem.

PS Sorry about the spelling... I am a Comp major, not an english major.

OK, The router has been out of the loop for a good while now, the cable modem is directly plugged into my main machine. That was about the first thing I did, sorry for not explaining it clearer (see post #1).

The sites I can't ping I can't throw a tracert to, heck not even a nslookup works. With other sites all three work fine. The cable company is, well, a cable company, and claim that some software is blocking at my end. What could that be ? I have no firewall installed, no proxy, Lmhost is not enabled, URL filters are not enabled and no security policies are set. The cable company just claims that they would have plenty of complaints if it was on their end, but I'm not convinced. So, thats where I stand, either I have to find out what is blocking or I have to present enough evidence to convince the cable guys that it really is at their end. And I can't get one more idea on what to do...

H.

DOS traceroute sucks, you should try a proper windows-gui based trace prog, like NeoTrace, or Visual Trace. They can do repeated traces, thereby giving average values as well as recording highest & lowest, & a bunch of other stuff.

Yeah, I hear you and I have NeoTrace, but as its not getting anywhere (can't reach the site) its of little help.

H.

Let's see how far it gets then. Run a trace, leave it going for a while, then post the results here.

Heh, tonight things are different -they are worse!

I can't ping ot tracert any sites, even if they work with IE6. Anyone have an explanation of that?

Neotrace doesn't work at all, just shows 2 points, my PC and the destination (see below). I can reach [url=www.yahoo.com]www.yahoo.com[/url] with IE6 without any problems.

NeoTrace Trace Version 3.25 Results
Target: [url=www.yahoo.com]www.yahoo.com[/url]
Date: 04-Jul-02 (Thursday), 22:46:52
Nodes: 2


Node Data
Node Net Reg IP Address Location Node Name
1 - - xxx.xxx.xxx.xxx x0.000N, 1x.000E Dirty Harrys PC
2 1 1 66.218.71.87 Unknown w8.scd.yahoo.com


Packet Data
Node High Low Avg Tot Lost
1 0 0 0 1 0
2 ---- ---- ---- 4 4

That's just damned weird. I think it may be time for a reinstall dude.

You bet its weird. Not one ping worked yesterday, still I was able to browse most sites.

As mentioned I've tried to flush back to a fresh XP install but that didn't help. Anyhow, now I've seen that the problem is varying (I used to be able to ping some but not all sites) I'm pretty convinced that the cable company is to blame, another thing is how I'll be able to convince them about it.

H.

Not challenging anyone's technological knowledge or anything like that but in reading the thread, I have to raise this question: Have you tested all the basics? Did you...
- Changed the NIC to see if it's a hardware problem?
- Changed routers/modems, wiring media, etc?
- Did you manually config the conn with a different IP?

Yes on all counts, except the wiring. And the wire can't plausibly be the part that excludes only certain sites all the time.

H.

Since you've removed the router from the picture, this isn't going to help, but I work for a membership association and have had reports of website blocking from all over the country.

I've asked each person if they have a cable modem - answer yes. Then I ask if they have a router - answer yes. I tell them to reset the router and try again, and every time it's worked for them. We have about 17 different websites, and they were unable to get to ANY of them with the URL or the IP - but once they reset the router, everything was fine. (different brands of routers, btw) I've been searching for an answer for quite sometime, and the only answer I can come up with is that if the website is trying to open too many connections - the router will block it. However, I have nothing except one popup window that I can figure out is trying to open connections. No JAVA, some java script that is client-side, setting one cookie (no call back required) - no database connection opening, etc.

Cable tells me to call the router people, the router people tell me to call the cable company.....you know how it goes.

Thanks for posting your solution, but this discussion was from about 2 years ago.

Likely the cause of your problem was some cached DNS entries.