1. On the Main tab, click DNS > Settings > GSLB > General .
   The General configuration screen opens.
2. Select the Synchronize check box.
3. In the Group Name field, type the name of the synchronization group to which you want this system to belong.
4. In the Time Tolerance field, type the maximum number of seconds allowed between the time settings on this system and the other systems in the synchronization group.
   The lower the value, the more often this system makes a log entry indicating that there is a difference.

   Tip: If you are using NTP, leave this setting at the default value of 10. In the event that NTP fails, the system uses the time_tolerance variable to maintain synchronization.
5. Click Update.

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 or Disabled.
   The default is Enabled, which specifies that the data center and its resources are available for load balancing.
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. Click Finished.
    Note: The gtmd process on each BIG-IP DNS system will attempt to establish an iQuery^® connection over port 4353 with each self IP address defined on each server in the BIG-IP DNS configuration of type BIG-IP. Allow port 4353 in your port lockdown settings for iQuery^® to work.
    The Server List screen opens displaying the new server in the list.

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 gtm_add script
   run gtm gtm_add
   1. Press the y key to start the gtm_add script.
   2. Type the IP address of the BIG-IP DNS system in the synchronization group to which you are adding this BIG-IP DNS system.
   3. Press Enter.
   4. If prompted, type the root password.
   5. Press Enter.

The new BIG-IP^® DNS system that you added to the network is a part of a BIG-IP DNS synchronization group. Changes you make to any system in the BIG-IP DNS synchronization group are automatically propagated to all other BIG-IP DNS systems in the group.