How is content monitoring different from downtime monitoring?

Downtime monitoring checks whether a webpage is up or down. Content monitoring checks that the text on the webpage is as it should be.

    How does content monitoring work?

A request is sent to the webpage every 3 minutes and the source code (i.e. the text) of the page is downloaded. This text is checked to see if it contains keywords that have been supplied by the user. If the text doesn't contain the keywords the site is marked as down, if it does the site is marked as up.

    When is content monitoring useful?

When a webpage goes down usually an http error is produced e.g. "500 Internal Server Error". Downtime monitoring will catch this error and the page will be marked as down. However, sometimes the page returns the expected response "200 OK" and has errors printed on the page. Downtime monitoring won't catch this error, however content monitoring will.

    What are the common circumstances where content monitoring is valuable?

1) Database errors are commonly caught by content monitoring but not by downtime monitoring. For example, when an SQL database is overloaded the message "SQL Error 1040: Too Many Connections" can be printed on a blank webpage.

2) Hacked websites, where the attacker replaces the website content with their own, can also be caught by content monitoring but will evade downtime monitoring.

3) Incorrect code on a webpage can throw an error on a blank webpage. This would be caught by content monitoring but missed by downtime monitoring.

    Are alert messages different for content monitoring?

Yes - the alert messages are different so that you can tell that the alert is due to content monitoring. The structure is: "URL is down: keywords don't match" or "URL is up: keywords match".

    Are content monitoring downtimes included in a website's uptime stats?

No, uptime monitoring and content monitoring are treated completely separately. However, all content monitoring downtimes are logged and records are viewable on the website stats page, under "Content (Keyword) Monitoring Logs".

    Will content monitoring cause high load to my server, since the page is downloaded every 3 minutes?

Downtime Monkey has taken some steps to prevent high load to your server:

1) The check frequency for content monitoring is reduced to every 3 minutes, as opposed to every minute for downtime monitoring.

2) Only text (i.e. the page source code) is downloaded from the webpage; images, videos etc. are ignored.

3) A partial download consisting of the first 5KB of the page is used when permitted by the server. However, not all servers allow this.

4) Where partial downloads are not permitted by the server the maximum page size of 50KB is permitted. Larger pages won't be accepted for monitoring.

    The webpage that I want to content monitor is too big - what can I do?

If the webpage source code is larger than 50KB (that's approximately 50,000 characters so very big!) and you want to apply content monitoring:

1) Set up your server to allow partial downloads of the page - this can be done by allowing the server to "accept range requests".

2) Reduce the size of the webpage to below 50KB.

3) Monitor a smaller page on the same website (or set up a small page for this reason) - usually errors that cause a content monitoring alert will effect the whole website.

    When I try to turn content monitoring on, I get the error: "keyword phrase does not match webpage content"?

1) The keyword phrase needs to be an exact match for the text in the source code of the webpage. The matching is case sensitive.

2) To make sure that you have the keyword phrase correct, copy and paste it from the website, rather than type it.

3) Use a keyword phrase that contains only letters and spaces, without special characters.

4) View the source code of the page (in your web browser, right click and select "View Page Source") and copy/paste a keyword phrase from the source code.

    When I try to turn content monitoring on, I get the error: "keywords must appear in the first 5KB of page content"?

To reduce load on your server (see above) only the first 5KB of the page is downloaded. Make sure that the keyword phrase that you use is close to the top of the page. For example, use the page title as it appears in the browser tab.

    When I try to turn content monitoring on, I get the error: "the webpage appears to be down or is redirected"?

Keyword monitoring can only be turned on for webpages that are up and responding - check that the webpage is up and doesn't redirect to another URL.

    When I try to turn content monitoring on, I get the error: "the webpage appears to be down or timing out"?

Keyword monitoring can only be turned on for webpages that are up and responding - check that the webpage is not running very slowly.

    When I try to turn content monitoring on, I get the error: "Fatal error: Allowed memory size of xxxxx bytes exhausted"?

To prevent against overloading of the Downtime Monkey server, the monitoring script is set to abort if a REALLY BIG page is checked for monitoring. Pages with 4MB or more of source code are likely to trigger this - note that webpages with this amount of source code are incredibly rare and this limit is in place largely to prevent malicious activity.