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HTTP Test
The HTTP test is designed for monitoring your HTTP servers
and web pages. Unlike services offered by other companies,
our HTTP test does much more than just downloading a web page!
Getting a web page successfully over the Internet depends
upon a number of factors. First, the client browser needs
to know the IP address of the server, and will use DNS to
perform the lookup. Poorly performing DNS servers will affect
their overall experience. There's also the question of whether
DNS queries and web pages have been cached somewhere along
the line. In-line objects (JPEG's, Flash documents, banner
ads etc) can be stored on different servers and will also
affect the overall page response.
Nexus Watch takes all of these points into consideration,
and performs a number of tests. The DNS response time is first
measured. To ensure that the results are consistent, the test
is performed twice and the second result logged. This ensures
that any DNS caching that may be configured to occur anywhere
along the path is taken into account. We can never prevent
an intermediary system from caching the requests (as they
are beyond our and your control), but we can force caching
to occur if it has been configured to do so by repeating the
test. This is the only way to produce consistent results.
Next, the web page is downloaded using a no-cache directive.
Caching of web pages is more significant than that of DNS
requests, and our test ensures that caching is disabled so
that the true performance of the HTTP server is measured.
The HTTP connection time is logged separately from the download
time of the page and all of its in-line objects. This helps
you distinguish between a slow network (where connection time
will be high), and a possible slow server (where transfer
rate is low, but connection time is low).
When you configure a report for a HTTP test, you are able
to see the results of these "sub-tests".
Of course, as with all of the Nexus Watch tests, the HTTP
test (including sub-tests) is performed simultaneously via
multiple ISPs to help you distinguish between problems with
you system and ISP problems.
The Nexus Watch HTTP test supports downloading of pages that
require logins. Just enter the login name and password on
the test configuration page.
Nexus Watch will repeat the test at intervals set by the
Polling Interval field on the test configuration page.
You may configure error and threshold events to watch out
for, and optionally have Nexus Watch send you an alert if
it sees them.
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