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

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

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 is important to monitor all of these servers to ensure that each is functioning properly.

About scheduling this monitor

If your DNS servers fail, users will start complaining that "everything's broken", so you should monitor them often. For example, 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 click 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 box in the advanced options section below.
Update every: Select how often the monitor should check the DNS server. The default interval is to run or update the monitor once every 10 minutes. Use the drop-down list to the right of the text box to specify another update interval in increments of seconds, minutes, hours, or days. The update interval must be 15 seconds or longer.
Title: Enter a title text for this monitor. This text is displayed in the group detail page, in report titles, and other places in the SiteScope interface. If you do not enter a title text, SiteScope will create a title based on the host, server, or URL being monitored.

Advanced Options

The Advanced Options section presents a number of ways to customize monitor behavior and display. Use this section to customize error and warning thresholds, disable the monitor, set monitor-to-monitor dependencies, customize display options, and enter other monitor specific settings required for special infrastructure environments. The options for this monitor type are described below. Complete the entries as needed and click the Add or Update button to save the settings.

Disable

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

Host address

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)

You use this option 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

By default, SiteScope 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. Click the Edit schedule link to create or edit a monitor schedule. For more information about working with monitor schedules, see the section on Schedule Preferences for Monitoring.

Monitor Description

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

Enter an optional description for this monitor that will make it easier to understand what the monitor does. For example, network traffic or main server response time. This description will be displayed on with each bar chart and graph in Management Reports and appended to the tool-tip displayed when you pass the mouse cursor over the status icon for this monitor on the monitor detail page.

Depends On

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 on which this monitor is dependent. Select None to remove any dependency.

Depends Condition

If you choose to make the running of this monitor dependent on the status of another monitor, select 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 on which it depends reports the condition selected in this option.

List Order

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 <&gt: 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 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 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.