How to test to see if a site is down

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Is there a free tool that will monitor your site and let you know how often
it is down?


Re: How to test to see if a site is down

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But I personally use a commercial service because it has extra features
like call phone numbers, multiple contacts at different intervals, etc.:

Edward Alfert - /
Coupon Code (Recurring $5/month Discount): newsgroup
Multiple Domain Hosting * Private Label Nameservers

Re: How to test to see if a site is down

This may be OT, but September 23rd we had a power drop in Copenhagen and
shortly after I received an email from a company called InternetSeer

!!On Tue Sep 23, 2003 at 09:20:05 AM EDT we were unable to reach your website:
!! /
!!due to the following reason: Host Not Found
!!As of Tue Sep 23, 2003 at 05:07:22 PM EDT we were able to access your
!!website again.
!!We discovered this error during our normal course of website content
!!checking for one of our search engine clients.
!!If you would like your website monitored for free and receive
!!notifications like this in the future, click here.

/Martin Hagstrøm

Re: How to test to see if a site is down

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This is a good question.   Here a few random thoughts..

The idea of having a company make regular, or random, test calls to the site
has the disadvantage of creating lots of traffic and does not identify short
breaks unless the requests are made very frequently - like every few
seconds.  Such a system might test only a limited variety of routes into the
server. Ask if it checks the DNS each time.

Maybe some log analysis programs have the ability to detect improbably long
silent periods in the log.

If you had enough traffic you might be able to run a monitoring system that
displayed traffic from all over the world in some graphical form and enabled
a human to see at a glance if some major incoming route was down.  The next
task would be to get a computer to do the failure detection.

I once had an outage that lasted nearly 48 hours when my registrar decided
to turn off the DNS server.  I had failed to notice that they had turned off
one of my DNS servers several months before and then the single one left
went down.  So moral is check that both of your DNS are actually functioning
from time to time.

It may be possible to get the server to send you an email if it ever reboots
due to a power outage.

I have no idea how to check incoming routes from far away places.  It would
be handy to have a reverse ping facility from some helpful computers in say
China, Japan, Australia etc.

Best regards, Eric.

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