Under the Configure option in the top navigation menu, select Filters. From here you can choose to edit or delete an existing filter under the Actions column or click the Add New Response Filter. Adding or editing a response filter displays the following fields.
Name: Be sure to specify a descriptive filter name so that you can identify the filter later in a drop-down list of other filters.
Description: Add additional explanations for what this filter is intended to accomplish.
In the Ignore an Error if the following error conditions apply section, you can specify multiple filters to help eliminate false positives and excessive alerts:
- Error is reported for less than (X) minutes – filters problems based on the frequency of an occurrence. For example, a five-minute setting filters out any problems that last for less than five minutes. Additionally, this option might be used for a brief rebooting of a web server when no alerts are desired.
- Error if it is not confirmed by (X) monitoring locations – filters errors based on the number of monitoring stations reporting the error. For example, a single monitoring station might not connect to a specific URL but other stations do connect, which signals that the problem lies with a backbone provider for that single station. Dotcom-Monitor recommends setting this filter value to two or higher to help filter out problems that are occurring on a specific backbone.
- Error detected in more than (X) tasks – filter alerts based on the number of task errors occurring in a monitored device. For example, a monitoring device might consist of tasks that access three web servers in a server farm. If two of the servers fail, the device will still work as constructed using only the remaining server. By default, Dotcom-Monitor would send an alert because the two servers are unavailable, but the monitoring device is still performing correctly only on a single server. If the filter is set at two, an alert is sent only when two tasks in the device fail.
- Owner Device is Down – If you have selected an Owner Device for a particular device, errors for the device this filter is applied to will be suppressed if the owner device is currently returning errors or is unavailable. For example, 10 different websites may be monitored as 10 different monitoring devices, but all the websites may be dependent on a single router. If the router fails, all 10 websites would become unavailable, and, by default, Dotcom-Monitor would send an alert for each website as an individual monitoring device.
Also, you can specify a filter to ignore specific error types in the Ignore an Error Type with specific Error Codes noted below section. This option filters out certain user-configurable errors. For example, DNS errors could be filtered out based on who is responsible for DNS server operations. You can create filters that will ignore specific errors that you know may occur and are not relevant to the goal of a specific device.