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Manual Chapter : Setting Up a BIG-IP DNS Redundant System Configuration

Applies To:

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BIG-IP LTM

  • 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

BIG-IP DNS

  • 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
Manual Chapter

Setting Up a BIG-IP DNS Redundant System Configuration

Overview: Configuring a BIG-IP DNS redundant system

You can configure BIG-IP® DNS in a redundant system configuration, which is a set of two BIG-IP DNS systems: one operating as the active unit, the other operating as the standby unit. If the active unit goes offline, the standby unit immediately assumes responsibility for managing DNS traffic. The new active unit remains active until another event occurs that would cause the unit to go offline, or you manually reset the status of each unit.
This basic configuration consists of only two BIG-IP DNS devices (active and standby), but the BIG-IP system now allows for a redundant system configuration to contain an arbitrary number of devices within a server.

Task Summary

Perform the following tasks to configure a BIG-IP DNS redundant system configuration.
Before you begin, ensure that the Setup utility was run on both devices. During the Setup process, you create VLANs internal and external and the associated floating and non-floating IP addresses, and VLAN HA and the associated non-floating self IP address. You also configure the devices to be in an active-standby redundant system configuration.

Defining an NTP server

Define a Network Time Protocol (NTP) server that both BIG-IP DNS systems use during configuration synchronization.
Perform these steps on both the active and standby systems.
  1. On the Main tab, click
    System
    Configuration
    Device
    NTP
    .
    The NTP Device configuration screen opens.
  2. For the
    Time Server Lookup List
     setting, in the
    Address
     field, type the IP address of the NTP that you want to add. Then click
    Add
    .
    If you did not disable DHCP before the first boot of the BIG-IP system, and if the DHCP server provides the information about your NTP server, then this field is automatically populated.
  3. For the
    Time Server List
     setting, in the
    Address
     field, type the IP address of the NTP server that you want to add. Then click
    Add
    .
    For this example, type
    192.168.5.15
    .
    If you did not disable DHCP before the first boot of the BIG-IP system, and if the DHCP server provides the information about your NTP server, then this field is automatically populated.
  4. For the
    Time Server List
     setting, in the
    Address
     field, type the IP address of an NTP server that you want to add. Then click
    Add
    .
    If you are using Dynamic Host Configuration Protocol (DHCP) to assign IP addresses, then the BIG-IP system automatically populates the
    Address
     field with the fully-qualified domain name (FQDN) of the NTP server.
  5. Repeat the preceding step as needed.
  6. Click
    Update
    .
During configuration synchronization, the systems use this time value to determine if any newer configuration files exist.

Creating listeners to identify DNS traffic

Create listeners to identify the DNS traffic that BIG-IP DNS handles. The best practice is to create four listeners: one with an IPv4 address that handles UDP traffic, and one with the same IPv4 address that handles TCP traffic; one with an IPv6 address that handles UDP traffic, and one with the same IPv6 address that handles TCP traffic.
DNS zone transfers use TCP port
53
. If you do not configure listeners for TCP the client might receive the error:
connection refused or TCP RSTs.
If you have multiple BIG-IP DNS systems in a device group, perform these steps on only one system.
  1. On the Main tab, click
    DNS
    Delivery
    Listeners
    .
    The Listeners List screen opens.
  2. Click
    Create
    .
    The Listeners properties screen opens.
  3. In the
    Name
     field, type a unique name for the listener.
  4. For the Destination setting, in the
    Address
     field, type an IPv4 address on which BIG-IP DNS listens for network traffic.
  5. In the Service area, from the
    Protocol
     list, select
    UDP
    .
  6. Click
    Finished
    .
Create another listener with the same IPv4 address and configuration, but select
TCP
 from the
Protocol
 list. Then, create two more listeners, configuring both with the same IPv6 address, but one with the UDP protocol and one with the TCP protocol.

Defining a data center

On BIG-IPDNS, create a data center to contain the servers that reside on a subnet of your network.
  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.
    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).
    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.
    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
    .
Now you can create server objects and assign them to this data center.
Repeat these steps to create additional data centers.

Defining a server and devices on the active BIG-IP system

Ensure that the data centers where the BIG-IP DNS systems reside exist in the configuration.
Using this procedure, create two servers on the active BIG-IP system, one that represents the active system and one that represents the standby system.
Perform this procedure on only the active system.
  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.
    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).
    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.
    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, add two devices (one that represents the active system and one that represents the standby system).
    1. Click
      Add
      .
    2. Type a name in the
      Device Name
       field.
    3. Type an external (public) IP address in the
      Address
       field.
    4. If you use NAT, type an internal (private) IP address in the
      Translation
       field.
    5. Click
      Add
      . Repeat the steps to add a second device, which represents the standby system.
    6. Click
      OK
      .
  10. From the
    Virtual Server Discovery
     list, select
    Disabled
    .
  11. Click
    Finished
    .
    The Server List screen opens displaying the new server in the list.

Enabling global traffic configuration synchronization

Enable global traffic configuration synchronization options and assign a name to the BIG-IP DNS synchronization group.
  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.
  4. In the
    Time Tolerance
     field, type the maximum age difference in seconds, between the sets of configuration files on the systems in a BIG-IP DNS configuration synchronization group.
  5. Select the
    Synchronize DNS Zone Files
     check box.
  6. Click
    Update
    .

Running the gtm_add script

You must run the
gtm_add
 script from the standby system.
You must perform this task from the command-line interface.
  1. On the new BIG-IP DNS system, log in to the command-line interface.
  2. Type
    gtm_add
    , and press Enter.
  3. Press the y key to start the
    gtm_add
     script.
  4. Type the IP address of the existing BIG-IP DNS system, and press Enter.
The
gtm_add
 script acquires configuration data from the active system; once this process completes, you have successfully created a redundant system consisting of two BIG-IP DNS systems.
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