The gtmd agent on BIG-IP^® DNS uses the iQuery^® protocol to communicate with the local big3d agent, and the big3d agents installed on other BIG-IP systems. The gtmd agent monitors both the availability of the BIG-IP systems, and the integrity of the network paths between the systems that host a domain and the local DNS servers that attempt to connect to that domain.

Communications between big3d and gtmd agents using iQuery

1. On the Main tab, click DNS > GSLB > Data Centers .
   The Data Center List screen opens.
2. Click Create.
   The New Data Center screen opens.
3. In the Name field, type a name to identify the data center.
   Important: The data center name is limited to 63 characters.
4. In the Location field, type the geographic location of the data center.
5. In the Contact field, type the name of either the administrator or the department that manages the data center.
6. From the Prober Preference list, select the preferred type of prober(s).

   Option	Description
   Inside Data Center	By default, select probers inside the data center.
   Outside Data Center	Select probers outside the data center.
   Specific Prober Pool	Select one of the Probers from the drop-down list. When you want to assign a Prober pool at the data center level. Note: Prober pools are not used by the bigip monitor.

7. From the Prober Fallback list, select the type of prober(s) to use if insufficient numbers of the preferred type are available.

   Option	Description
   Any Available	By default, select any available prober.
   Inside Data Center	Select probers inside the data center.
   Outside Data Center	Select probers outside the data center.
   None	No fallback probers are selected. Prober fallback is disabled.
   Specific Prober Pool	Select one of the Probers from the drop-down list. When you want to assign a Prober pool at the data center level.

8. From the State list, select Enabled.
9. Click Finished.

1. On the Main tab, click DNS > GSLB > Servers .
   The Server List screen opens.
2. Click Create.
   The New Server screen opens.
3. In the Name field, type a name for the server.
   Important: Server names are limited to 63 characters.
4. From the Product list, select BIG-IP System.
5. From the Data Center list, select the data center where the server resides.
6. From the Prober Preference list, select the preferred type of prober(s).

   Option	Description
   Inherit From Data Center	By default, a server inherits the prober preference selection assigned to the data center in which the server resides.
   Inside Data Center	A server selects the probers from inside the data center where the server resides.
   Outside Data Center	A server selects the probers from outside the data center where the server resides.
   Specific Prober Pool	Select one of the Prober pools from the drop-down list. When assigning the Prober pool at the server level. Note: Prober pools are not used by the bigip monitor.

7. From the Prober Fallback list, select the type of prober(s) to be used if insufficient numbers of the preferred type are available.

   Option	Description
   Inherit From Data Center	By default, a server inherits the prober fallback selection assigned to the data center in which the server resides.
   Any Available	For selecting any available prober.
   Inside Data Center	A server selects probers from inside the data center where the server resides.
   Outside Data Center	A server selects probers from outside the data center where the server resides.
   None	No fallback probers are selected. Prober fallback is disabled.
   Specific Prober Pool	Select one of the Probers from the drop-down list. When you want to assign a Prober pool at the server level.

8. From the State list, select Enabled.
9. In the BIG-IP System Devices area, click Add to add a device (server).
   1. Type a name in the Device Name field.
   2. Type an external (public) non-floating IP address in the Address field.
   3. If you use NAT, type an internal (private) IP address in the Translation field, and then click Add.
   4. Click Add.
   5. Click OK.
10. From the Configuration list, select Advanced.
    Additional controls display on the screen.
11. In the Health Monitors area, assign the bigip monitor to the server by moving it from the Available list to the Selected list.
12. From the Availability Requirements list, select one of the following and enter any required values.

    Option	Description
    All Health Monitors	By default, specifies that all of the selected health monitors must be successful before the server is considered up (available).
    At Least	The minimum number of selected health monitors that must be successful before the server is considered up.
    Require	The minimum number of successful probes required from the total number of probers requested.

13. From the Virtual Server Discovery list, select how you want virtual servers to be added to the system.

    Option	Description
    Disabled	The system does not use the discovery feature to automatically add virtual servers. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM® combo system when you plan to manually add virtual servers to the system, or if your network uses multiple route domains.
    Enabled	The system uses the discovery feature to automatically add and delete virtual servers. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.
    Enabled (No Delete)	The system uses the discovery feature to automatically add virtual servers and does not delete any virtual servers that already exist in the configuration. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.

14. In the Virtual Server List area, if you selected Disabled from the Virtual Server Discovery list, specify the virtual servers that are resources on this server.
    1. In the Name field, type the name of the virtual server.
    2. In the Address field, type the IP address of the virtual server.
    3. From the Service Port list, select the port the server uses.
    4. Click Add.
15. From the Link Discovery list, select how you want links to be added to the system.

    Option	Description
    Disabled	The system does not use the discovery feature to automatically add links. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM combo system when you plan to manually add links to the system.
    Enabled	The system uses the discovery feature to automatically add and delete links. Use this option for a BIG-IP DNS/LTM combo system when you want BIG-IP DNS to discover links.
    Enabled (No Delete)	The system uses the discovery feature to automatically add links and does not delete any links that already exist in the configuration. Use this option for a BIG-IP DNS/LTM combo system when you want BIG-IP DNS to discover links.

16. Click Finished.
    The Server List screen opens displaying the new server in the list.

1. On the Main tab, click DNS > GSLB > Servers .
   The Server List screen opens.
2. Click Create.
   The New Server screen opens.
3. In the Name field, type a name for the server.
   Important: Server names are limited to 63 characters.
4. From the Product list, select BIG-IP System.
5. From the Data Center list, select the data center where the server resides.
6. From the Prober Preference list, select the preferred type of prober(s).

   Option	Description
   Inherit From Data Center	By default, a server inherits the prober preference selection assigned to the data center in which the server resides.
   Inside Data Center	A server selects the probers from inside the data center where the server resides.
   Outside Data Center	A server selects the probers from outside the data center where the server resides.
   Specific Prober Pool	Select one of the Prober pools from the drop-down list. When assigning the Prober pool at the server level. Note: Prober pools are not used by the bigip monitor.

7. From the Prober Fallback list, select the type of prober(s) to be used if insufficient numbers of the preferred type are available.

   Option	Description
   Inherit From Data Center	By default, a server inherits the prober fallback selection assigned to the data center in which the server resides.
   Any Available	For selecting any available prober.
   Inside Data Center	A server selects probers from inside the data center where the server resides.
   Outside Data Center	A server selects probers from outside the data center where the server resides.
   None	No fallback probers are selected. Prober fallback is disabled.
   Specific Prober Pool	Select one of the Probers from the drop-down list. When you want to assign a Prober pool at the server level.

8. From the State list, select Enabled.
9. In the BIG-IP System Devices area, click Add to add a device (server).
   1. Type a name in the Device Name field.
   2. Type an external (public) non-floating IP address in the Address field.
   3. If you use NAT, type an internal (private) IP address in the Translation field, and then click Add.
   4. Click Add.
   5. Click OK.
10. From the Configuration list, select Advanced.
    Additional controls display on the screen.
11. In the Health Monitors area, assign the bigip monitor to the server by moving it from the Available list to the Selected list.
12. From the Availability Requirements list, select one of the following and enter any required values.

    Option	Description
    All Health Monitors	By default, specifies that all of the selected health monitors must be successful before the server is considered up (available).
    At Least	The minimum number of selected health monitors that must be successful before the server is considered up.
    Require	The minimum number of successful probes required from the total number of probers requested.

13. From the Virtual Server Discovery list, select how you want virtual servers to be added to the system.

    Option	Description
    Disabled	The system does not use the discovery feature to automatically add virtual servers. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM® combo system when you plan to manually add virtual servers to the system, or if your network uses multiple route domains.
    Enabled	The system uses the discovery feature to automatically add and delete virtual servers. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.
    Enabled (No Delete)	The system uses the discovery feature to automatically add virtual servers and does not delete any virtual servers that already exist in the configuration. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.

14. In the Virtual Server List area, if you selected Disabled from the Virtual Server Discovery list, specify the virtual servers that are resources on this server.
    1. In the Name field, type the name of the virtual server.
    2. In the Address field, type the IP address of the virtual server.
    3. From the Service Port list, select the port the server uses.
    4. Click Add.
15. From the Link Discovery list, select how you want links to be added to the system.

    Option	Description
    Disabled	The system does not use the discovery feature to automatically add links. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM combo system when you plan to manually add links to the system.
    Enabled	The system uses the discovery feature to automatically add and delete links. Use this option for a BIG-IP DNS/LTM combo system when you want BIG-IP DNS to discover links.
    Enabled (No Delete)	The system uses the discovery feature to automatically add links and does not delete any links that already exist in the configuration. Use this option for a BIG-IP DNS/LTM combo system when you want BIG-IP DNS to discover links.

16. Click Finished.
    The Server List screen opens displaying the new server in the list.
17. In the Server List screen, select the name of the new server.
18. Select the Virtual Servers tab.
19. From the Virtual Servers list, select the name of a virtual server previously created.
    A Virtual Server list screen opens.
20. From the Configuration list, select Advanced.
    Additional controls display on the screen.
21. In the Health Monitors area, assign the bigip monitor to the server by moving it from the Available list to the Selected list.
22. Click Update.

1. Log in as root to the BIG-IP DNS system you are adding to your network.
2. Run this command to access tmsh:
   tmsh
3. Run this command to run the big3d_install script:
   run gtm big3d_install <IP_addresses_of_target BIG-IP_systems>
   The script instructs BIG-IP DNS to connect to each specified BIG-IP system.
4. If prompted, enter the root password for each system.

1. Log in as root to the BIG-IP DNS system you are installing on your network.
2. Run this command to access tmsh.
   tmsh
3. Run this command to run the bigip_add utility:
   run gtm bigip_add <IP_addresses_of_BIG-IP_LTM_systems>
   The utility exchanges SSL certificates so that each system is authorized to communicate with the other.

You now have an implementation in which the BIG-IP^® systems can communicate with each other. DNS can now use the other BIG-IP systems when load balancing DNS queries, and can acquire statistics and status information for the virtual servers these systems manage.