Manual Chapter : Monitors Tasks

Applies To:

  • BIG-IP DNS

    21.0.0, 17.5.1, 17.5.0, 17.1.3, 17.1.2, 17.1.1, 17.1.0, 17.0.0, 16.1.6, 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0, 14.1.5, 14.1.4, 14.1.3, 14.1.2, 14.1.0, 14.0.1, 14.0.0

Updated Date: 07/07/2026

Monitors Tasks

Create an SNMP monitor to monitor a third-party server running SNMP.

  1. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  2. On the Main tab, click DNS > GSLB > Monitors.

    The Monitor List screen opens.

  3. Click Create.

    The New Monitor screen opens.

  4. Type a name for the monitor.

    Important: Monitor names are limited to 63 characters.

  5. From the Type list, select one of these options:

SNMP DCA

Use this monitor to specify new values for CPU, memory, and disk metrics.

SNMP DCA Base

Use this monitor to specify values for metrics other than CPU, memory, and disk usage.

  1. From the Type list, select SNMP.

  2. Click Finished.

Before creating a custom monitor, you must decide on a monitor type.

You can create a custom monitor when the values defined in a pre-configured monitor do not meet your needs, or no pre-configured monitor exists for the type of monitor you are creating.

Important: When defining values for custom monitors, make sure you avoid using any values that are on the list of reserved keywords.

  1. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  2. Click Create.

    The New Monitor screen opens.

  3. In the Name field, type a name for the monitor.

  4. From the Type list, select the type of monitor.

    The screen refreshes, and displays the configuration options for the monitor type.

  5. From the Import Monitor list, select an existing monitor.

    The new monitor inherits initial configuration values from the existing monitor.

  6. From the Configuration list, select Advanced.

    This selection makes it possible for you to modify additional default settings.

  7. Configure all settings shown.

  8. Click Finished.

You can display a monitor and view the settings and values.

Note: You can manage only those monitors that you have permission to manage, based on your user role and partition access assignment.

  1. On the Main tab, click DNS > GSLB > Monitors.

    The Monitor List screen opens.

  2. On the Main tab, click Link Controller > Monitors.

    The Monitor List screen opens.

  3. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  4. Click a monitor name in the list.

    The monitor’s properties screen opens, showing the monitor’s settings and values.

You can view the settings and values for the monitor.

Prior to deleting a monitor, you must remove all existing monitor associations.

You can delete obsolete or unused monitors.

Note: You can manage only those monitors that you have permission to manage, based on your user role and partition access assignment.

  1. On the Main tab, click DNS > GSLB > Monitors.

    The Monitor List screen opens.

  2. On the Main tab, click Link Controller > Monitors.

    The Monitor List screen opens.

  3. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  4. Select the Select check box for the monitor that you want to delete.

  5. Click Delete.

    A confirmation message appears.

  6. Click Delete.

The monitor is deleted.

Before creating a monitor, you must decide on a monitor type.

A custom HTTP monitor enables you to send a command to a server and examine that server’s response, thus ensuring that it is serving appropriate content.

Note: An HTTP monitor can monitor Outlook Web Access (OWA) in Microsoft Exchange Server 2007 and MicrosoftSharePoint 2007 web sites that require NT LAN Manager (NTLM) authentication. NTLM authentication requires a send string that complies with HTTP/1.1, a user name, and a password.

  1. On the Main tab, click DNS > GSLB > Monitors.

    The Monitor List screen opens.

  2. On the Main tab, click Link Controller > Monitors.

    The Monitor List screen opens.

  3. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  4. In the Name field, type a name for the monitor.

  5. From the Type list, select HTTP.

    The screen refreshes, and displays the configuration options for the HTTP monitor type.

  6. From the Parent Monitor list, select http.

    The new monitor inherits initial configuration values from the existing monitor.

  7. From the Configuration list, select Advanced.

    This selection makes it possible for you to modify additional default settings.

  8. In the Interval field, type a number that indicates, in seconds, how frequently the system issues the monitor check. The default is 30 seconds.

    The frequency of a monitor check must be greater than the value of the global-level Heartbeat Interval setting. Otherwise, the monitor can acquire out-of-date data.

  9. In the Timeout field, type a number that indicates, in seconds, how much time the target has to respond to the monitor check. The default is 120 seconds.

    If the target responds within the allotted time period, it is considered up. If the target does not respond within the time period, it is considered down.

  10. In the Probe Timeout field, type a number that indicates the number of seconds after which the system times out the probe request to the system. The default is 5 seconds.

  11. For the Ignore Down Response setting, do one of the following:

    • Accept the No default option.
    • Select the Yes option to specify that the monitor accepts more than one probe attempt per interval.

  12. In the Send String field, type a text string that the monitor sends to the target resource.

    The default string is GET /. This string retrieves a default file from the web site.

    Type a fully qualified path name, for example, GET /www/example/index.html, if you want to retrieve a specific web site page.

  13. In the Interval field type a number that indicates, in seconds, how frequently the system issues the monitor check. The default is 5 seconds.

    The frequency of a monitor check must be greater than the value of the global-level Heartbeat Interval setting. Otherwise, the monitor can acquire out-of-date data.

  14. For the Up Interval setting, specify whether to use the up interval:

    • If you do not want to use the up interval, retain the default, Disabled.
    • To use the up interval, select Enabled, and specify how often you want the system to verify the health of a resource that is up.

  15. In the Time Until Up field, type a number that indicates the number of seconds to wait after a resource first responds correctly to the monitor before setting the resource to up.

    The default value is 0 (zero), which disables this option.

  16. In the Timeout field, type a number that indicates, in seconds, how much time the target has to respond to the monitor check. The default is 30 seconds.

    If the target responds within the allotted time period, it is considered up. If the target does not respond within the time period, it is considered down.

  17. For Manual Resume, specify whether the system automatically enables the monitored resource when the monitor check is successful.

    This setting applies only when the monitored resource has failed to respond to a monitor check.

Yes

The system does nothing when the monitor check succeeds, and you must manually enable the monitored resource.

No

The system automatically re-enables the monitored resource after the next successful monitor check.

  1. In the Send String field, type a text string that the monitor sends to the target resource.

    The default string is GET /\r\n. This string retrieves a default file from the web site.

    Important: Send string syntax depends upon the HTTP version. Please observe the following conventions.

    Version Convention
    HTTP 0.9 "GET /\n" or "GET /\r\n".
    HTTP 1.0 "GET / HTTP/1.0\r\n\r\n" or "GET / HTTP/1.0\n\n"
    HTTP 1.1 "GET / HTTP/1.1\r\nHost: server.com\r\n\r\n" or "GET / HTTP/1.1\r\nHost: server.com\r\nConnection: close\r\n\r\n"
    HTTP/2 "GET /\r\n"

    Type a fully qualified path name, for example, "GET /www/example/index.html\r\n", if you want to retrieve a specific web site page.

  2. In the Receive String field, type a regular expression that represents the text string that the monitor looks for in the returned resource.

    The most common receive expressions contain a text string that is included in an HTML file on your site. The text string can be regular text, HTML tags, or image names.

    Note: If you do not specify both a send string and a receive string, the monitor performs a simple service check and connect only.

  3. In the Receive Disable String field, type a regular expression that represents the text string that the monitor looks for in the returned resource.

    Use a Receive String value together with a Receive Disable String value to match the value of a response from the origin web server and create one of three states for a pool member or node: Up (Enabled), when only Receive String matches the response, or when both Receive String and Receive Disable String match the response; Up (Disabled), when only Receive Disable String matches the response; or Down, when neither Receive String nor Receive Disable String matches the response.

    Note: If you choose to set the Reverse setting to Yes, the monitor marks the pool, pool member, or node Down when the test is successful.

  4. Type a name in the User Name field.

  5. Type a password in the Password field.

  6. For the Reverse setting, specify whether you want the system to work in reverse mode:

    • If you want the system to work normally, retain the No default option.
    • If you want the system to mark the pool, pool member, or node Down when the test is successful, select the Yes option.

  7. For the Transparent setting, specify whether you want the monitor to operate in transparent mode:

    • If not, accept the No default option.
    • To use a path through the associated pool members or nodes to monitor the aliased destination, select the Yes option.

  8. For the Alias Address setting, specify an alias IP address:

    • Retain the *All Addresses default option.
    • Type an alias IP address for the monitor to verify, on behalf of the pools or pool members with which the monitor is associated. If the health check for the alias address is successful, the system marks all associated objects up. If the health check for the alias address is not successful, then the system marks all associated objects down.

  9. For the Alias Service Port setting, specify an alias port or service for the monitor to check:

    • Accept the *All Ports default option.
    • Select an alias port or service for the monitor to check, on behalf of the pools or pool members with which the monitor is associated. If the health check for the alias port or service is successful, the system marks all associated objects up. If the health check for the alias port or service is not successful, then the system marks all associated objects down.

The HTTP monitor is configured to monitor HTTP traffic.

Before creating a monitor, you must decide on a monitor type.

A custom HTTPS monitor enables you to verify the Hypertext Transfer Protocol Secure (HTTPS) service by attempting to receive specific content from a web page protected by Secure Socket Layer (SSL) security.

  1. On the Main tab, click Local Traffic > Monitors.

    The Monitors List screen opens.

  2. Click Create.

    The New Monitor screen opens.

  3. In the Name field, type a name for the monitor.

  4. From the Type list, select HTTPS.

    The screen refreshes, and displays the configuration options for the HTTPS monitor type.

  5. From the Parent Monitor list, select an existing monitor.

    The new monitor inherits initial configuration values from the existing monitor.

  6. From the Configuration list, select Advanced.

    This selection makes it possible for you to modify additional default settings.

  7. In the Interval field type a number that indicates, in seconds, how frequently the system issues the monitor check. The default is 5 seconds.

    The frequency of a monitor check must be greater than the value of the global-level Heartbeat Interval setting. Otherwise, the monitor can acquire out-of-date data.

  8. For the Up Interval setting, specify whether to use the up interval:

    • If you do not want to use the up interval, retain the default, Disabled.
    • To use the up interval, select Enabled, and specify how often you want the system to verify the health of a resource that is up.

  9. In the Time Until Up field, type a number that indicates the number of seconds to wait after a resource first responds correctly to the monitor before setting the resource to up.

    The default value is 0 (zero), which disables this option.

  10. In the Timeout field, type a number that indicates, in seconds, how much time the target has to respond to the monitor check. The default is 16 seconds.

    If the target responds within the allotted time period, it is considered up. If the target does not respond within the time period, it is considered down.

  11. For Manual Resume, specify whether the system automatically enables the monitored resource when the monitor check is successful.

    This setting applies only when the monitored resource has failed to respond to a monitor check.

Yes

The system does nothing when the monitor check succeeds, and you must manually enable the monitored resource.

No

The system automatically re-enables the monitored resource after the next successful monitor check.

  1. In the Send String field, type a text string that the monitor sends to the target resource.

    The default string is GET /\r\n. This string retrieves a default file from the web site.

    Important: Send string syntax depends upon the HTTP version. Please observe the following conventions.

    Version Convention
    HTTP 0.9 "GET /\n" or "GET /\r\n".
    HTTP 1.0 "GET / HTTP/1.0\r\n\r\n" or "GET / HTTP/1.0\n\n"
    HTTP 1.1 "GET / HTTP/1.1\r\nHost: server.com\r\n\r\n" or "GET / HTTP/1.1\r\nHost: server.com\r\nConnection: close\r\n\r\n"
    HTTP/2 "GET /\r\n"

    Type a fully qualified path name, for example, "GET /www/example/index.html\r\n", if you want to retrieve a specific web site page.

  2. In the Receive String field, type a regular expression that represents the text string that the monitor looks for in the returned resource.

    The most common receive expressions contain a text string that is included in an HTML file on your site. The text string can be regular text, HTML tags, or image names.

    Note: If you do not specify both a send string and a receive string, the monitor performs a simple service check and connect only.

  3. In the Receive Disable String field, type a regular expression that represents the text string that the monitor looks for in the returned resource.

    Use a Receive String value together with a Receive Disable String value to match the value of a response from the origin web server and create one of three states for a pool member or node: Up (Enabled), when only Receive String matches the response, or when both Receive String and Receive Disable String match the response; Up (Disabled), when only Receive Disable String matches the response; or Down, when neither Receive String nor Receive Disable String matches the response.

    Note: If you choose to set the Reverse setting to Yes, the monitor marks the pool, pool member, or node Down when the test is successful.

  4. From the SSL Profile list, select an option for the profile:

    • To specify no SSL profile, accept the default, None.
    • To use a profile, select an SSL Profile from the list of the available serverssl profiles in the BIG-IP system.

  5. Type a name in the User Name field.

  6. Type a password in the Password field.

  7. For the Reverse setting, specify whether you want the system to work in reverse mode:

    • If you want the system to work normally, retain the No default option.
    • If you want the system to mark the pool, pool member, or node Down when the test is successful, select the Yes option.

  8. For the Transparent setting, specify whether you want the monitor to operate in transparent mode:

    • If not, accept the No default option.
    • To use a path through the associated pool members or nodes to monitor the aliased destination, select the Yes option.

  9. For the Alias Address setting, specify an alias IP address:

    • Retain the *All Addresses default option.
    • Type an alias IP address for the monitor to verify, on behalf of the pools or pool members with which the monitor is associated. If the health check for the alias address is successful, the system marks all associated objects up. If the health check for the alias address is not successful, then the system marks all associated objects down.

  10. For the Alias Service Port setting, specify an alias port or service for the monitor to check:

    • Accept the *All Ports default option.
    • Select an alias port or service for the monitor to check, on behalf of the pools or pool members with which the monitor is associated. If the health check for the alias port or service is successful, the system marks all associated objects up. If the health check for the alias port or service is not successful, then the system marks all associated objects down.

The HTTPS monitor is configured to monitor HTTPS traffic.

When you are done, associate the HTTPS monitor with a server, pool, pool member, or node.