Why can I see my website even though it's down

Question

I'm wondering if anyone knows how this happens? My website is down, but every computer on my internet connection/router can see it. I've cleared my cache etc, but another computer in the house shouldn't be seeing a site that's offline. How weird?

It's hosted remotely, not on my network or anything.

Answer 1

i know it's down cause i asked my friends in other locations to look at it. then i ran a test using this site i found.

http://www.websitepulse.com/help/tools.php

i'm switching hosts and we're dealing with my main domain name. that's the other reason i expected this interuption. i just want to know when it's finally switched.

is ISP cache a bad thing?

Answer 2

Your ISP is probably caching the content.

Answer 3

What DNS servers are your friends using? Same as yours?

Answer 4

Internet provider cache maybe.

Answer 5

Do you know the IP address of your web server? Do you have direct access to the Internet on port 80?

Tell if your server is up or down by doing the following

telnet 255.255.255.255 80

Where 255.255.255.255 is your web server's IP address. On windows the screen will go blank if the server answers. Then type

GET / HTTP/1.0

And hit enter twice. You should see the content of your default page. If your running as a virtual host, you'll probably need to use HTTP/1.1 and the Hostname tag.

GET / HTTP/1.1
Host: www.yourservername.com

There is one return after HTTP/1.1 and two returns after your hostname. If you get content (the correct content) back from your web server it is definitely not down. If the server fails to connect then your web server is really down, and the content your computers are seeing could be any of the following:

• local page cache
• local proxy server
• ISP proxy server
• local ARP poisoning attack redirecting you to attacker's local web server which mirrored your site.
• DNS poisoning to direct your browsers to someone else's web server which mirrored your site.

If your site is up, but geographically separated folks can't see your site, it is most likely a DNS issue or an ISP level routing issue.

A good tool to check for DNS issues is OpenDNS's CacheCheck. As for the routing issue, the best bet is to call your web hosting company and see if they've had any other complaints from their other customers, or if they are currently working on a routing issue.

Answer 6

The first question to ask yourself is, how certain are you that it's down? If computer A can access it and computer B cannot, either one could be "right":

1. The site could be down, and computer A could be looking at a cached version from the ISP.

2. The site could be up, but computer B could be having general internet connectivity problems, or problems accessing this site in particular (bad DNS cache, etc.)

One way to tell is to add some new content to the site (via FTP or an in-place content management system like wordpress, for example) and see if the computer that can access it (computer A) can see the changes. If so, then you're looking at a "live" site, where the pages are being served directly from the server. (If the server is active and runs web software like PHP or ASP, then that would be another way to "prove" that the site is up and running).