SiteScope User's Guide

DNS Monitor

The SiteScope DNS Monitor checks a Domain Name Server via the network. It verifies that the DNS server is accepting requests, and also verifies that the address for a specific domain name can be found.

Each time the DNS Monitor runs, it returns a status and writes it in the monitoring log file.

Usage Guidelines

Why should I use this monitor?

If your DNS server is not working properly, you won't be able to get out on the network and people trying to reach your server won't be able to find it. Therefore, it's important that you monitor your DNS server(s) to ensure that they are working properly.

What should I monitor?

Most companies have both a primary and a secondary DNS server. If your company employs a firewall, these servers may sit outside the firewall with another DNS server located inside the firewall. This internal DNS server provides domain name service for internal machines. It's important to monitor all of these servers to ensure that each is functioning properly.

How should I schedule my monitors?

If your DNS servers fail, people will start complaining that "everything's broken", so you should monitor them often. Let's assume that you have both a primary and secondary DNS server outside your firewall and an internal DNS server inside your firewall. Your internal server is critical, so you should monitor that one every 2 - 5 minutes. That's also a good interval for your primary DNS server that sits outside of your firewall. You can monitor the secondary DNS server less often. Every 10 or 15 minutes should be fine.

Completing the DNS Monitor Form

To display the DNS Monitor Form, either click the Edit link for an existing DNS Monitor in a monitor table, or click the add a Monitor link on a group's detail page and choose the "Add DNS Monitor" link.

Complete the items on the DNS Monitor form as follows. When the required items are complete, click the "Add Monitor" button.

Server Address: Enter the IP address of the DNS server that you want to monitor (for example, 206.168.191.1).
Host Name: Enter the host name to lookup (for example, demo.thiscompany.com). If you only want to verify that your DNS server is operating, the host name you enter here can be any valid host name or domain name. To verify that a domain name resolves to a specific IP address, enter the IP address that corresponds to the host name you enter in the Host address entry in the advanced options section below.
Update every: Enter how frequently the monitor should check the DNS server. The drop-down list to the right of the text box lets you specify time increments of seconds, minutes, hours, or days. You must specify a time increment of at least 15 seconds.
Title (Optional): Enter a name for this monitor. This name appears in the Name text box on the monitor table when you open the group's detail page. If you don't enter a name, a default name will be created.

Advanced Options

The advanced options give you the ability to customize error and warning thresholds. If you choose not to set them, SiteScope will use preset defaults if available. If a default is not available, SiteScope will not be able to utilize the condition.

Disable

Check this box to temporarily disable this monitor and any associated alerts. To enable the monitor again, clear the box.

Host address (Optional)

Optionally, you can use the DNS monitor to verify that a host name or domain name resolves to the correct IP address or addresses. Enter the IP address or addresses that are mapped to the Host Name (domain name) entered above.

Verify Error

Check this box if you want SiteScope to automatically run this monitor again if it detects an error. When an error is detected, the monitor will immediately be scheduled to run again once.

Note: In order to change the run frequency of this monitor when an error is detected, use the Update every (on errors) option below.

Note: The status returned by the Verify Error run of the monitor will replace the status of the originally scheduled run that detected an error. This may cause the loss of important performance data if the data from the verify run is different than the initial error status.

Warning: Use of this option across many monitor instances may result in significant monitoring delays in the case that multiple monitors are rescheduled to verify errors at the same time.

Update Every (on error)

This options allows you to set a new monitoring interval for monitors that have registered an error condition. For example, you may want SiteScope to monitor this item every 10 minutes normally, but as often as every 2 minutes if an error has been detected. Note that this increased scheduling will also affect the number of alerts generated by this monitor.

Schedule (Optional)

By default, SiteScope's monitors are enabled every day of the week. You may, however, schedule your monitors to run only on certain days or on a fixed schedule. Choose the Edit schedule link to create or edit a monitor schedule. For information about creating schedules, read these instructions.

Monitor Description (Optional)

Enter additional information about this monitor. The Monitor Description can include HTML tags such as the <BR> <HR>, and <B> tags to control display format and style. The description will appear on the Monitor Detail page.

Report Description (Optional)

Enter a description for this monitor that will make it easier to understand what this monitor does. The description will appear on Management Reports and on the info list for a monitor.

Depends On (Optional)

To make the running of this monitor dependent on the status of another monitor or monitor group, use the drop-down list to select the monitor or group on which this monitor is dependent. Select None to remove any dependency.

Depends Condition (Optional)

If you choose to make the running of this monitor dependent on the status of another monitor, choose the status condition that the other monitor or monitor group should have in order for the current monitor to run normally. The current monitor will be run normally as long as the monitor or group on which it depends reports the condition selected in this option.

List Order (Optional)

By default, new monitors are listed last on the Monitor Detail page. You may use this drop-down list to choose a different placement for this monitor.

Error if

Set the conditions under which the DNS monitor should report an error status. To set the error threshold, choose either status <>: 200 (the default setting) if you only want to know if the DNS returned an error or choose round trip time from the drop-down list and then, in the text entry box, enter the lowest time value (in milliseconds) which should trigger a error condition . The time values must be entered as a whole number.

Warning if: Set the conditions under which the DNS monitor should report a warning status. To set the warning threshold, choose round trip time from the drop-down list and then, in the text entry box, enter the lowest time value (in milliseconds) which should trigger a warning condition. The time values must be entered as a whole number.
Good if: By default, this monitor returns a status of "good" if the monitor received a status code of 200. You can change it to return a good value based upon round-trip time.