Manual Chapter :
Setting Up a BIG-IP DNS Redundant System Configuration
Applies To:
Show VersionsBIG-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
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.
- On the Main tab, click.The NTP Device configuration screen opens.
- For theTime Server Lookup Listsetting, in theAddressfield, type the IP address of the NTP that you want to add. Then clickAdd.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.
- For theTime Server Listsetting, in theAddressfield, type the IP address of the NTP server that you want to add. Then clickAdd.For this example, type192.168.5.15.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.
- For theTime Server Listsetting, in theAddressfield, type the IP address of an NTP server that you want to add. Then clickAdd.If you are using Dynamic Host Configuration Protocol (DHCP) to assign IP addresses, then the BIG-IP system automatically populates theAddressfield with the fully-qualified domain name (FQDN) of the NTP server.
- Repeat the preceding step as needed.
- ClickUpdate.
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. If you
have multiple BIG-IP DNS systems in a device group, perform these steps on only one system.
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.
- On the Main tab, click.The Listeners List screen opens.
- ClickCreate.The Listeners properties screen opens.
- In theNamefield, type a unique name for the listener.
- For the Destination setting, in theAddressfield, type an IPv4 address on which BIG-IP DNS listens for network traffic.
- In the Service area, from theProtocollist, selectUDP.
- ClickFinished.
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.
- On the Main tab, click.The Data Center List screen opens.
- ClickCreate.The New Data Center screen opens.
- In theNamefield, type a name to identify the data center.The data center name is limited to 63 characters.
- In theLocationfield, type the geographic location of the data center.
- In theContactfield, type the name of either the administrator or the department that manages the data center.
- From theProber Preferencelist, select the preferred type of prober(s).Inside Data CenterBy default, select probers inside the data center.Outside Data CenterSelect probers outside the data center.Specific Prober PoolSelect 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.
- From theProber Fallbacklist, select the type of prober(s) to use if insufficient numbers of the preferred type are available.Any AvailableBy default, select any available prober.Inside Data CenterSelect probers inside the data center.Outside Data CenterSelect probers outside the data center.NoneNo fallback probers are selected. Prober fallback is disabled.Specific Prober PoolSelect one of the Probers from the drop-down list. When you want to assign a Prober pool at the data center level.
- From theStatelist, selectEnabled.
- ClickFinished.
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.
- On the Main tab, click.The Server List screen opens.
- ClickCreate.The New Server screen opens.
- In theNamefield, type a name for the server.Server names are limited to 63 characters.
- From theProductlist, selectBIG-IP System.
- From theData Centerlist, select the data center where the server resides.
- From theProber Preferencelist, select the preferred type of prober(s).Inherit From Data CenterBy default, a server inherits the prober preference selection assigned to the data center in which the server resides.Inside Data CenterA server selects the probers from inside the data center where the server resides.Outside Data CenterA server selects the probers from outside the data center where the server resides.Specific Prober PoolSelect 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.
- From theProber Fallbacklist, select the type of prober(s) to be used if insufficient numbers of the preferred type are available.Inherit From Data CenterBy default, a server inherits the prober fallback selection assigned to the data center in which the server resides.Any AvailableFor selecting any available prober.Inside Data CenterA server selects probers from inside the data center where the server resides.Outside Data CenterA server selects probers from outside the data center where the server resides.NoneNo fallback probers are selected. Prober fallback is disabled.Specific Prober PoolSelect one of the Probers from the drop-down list. When you want to assign a Prober pool at the server level.
- From theStatelist, selectEnabled.
- In the BIG-IP System Devices area, add two devices (one that represents the active system and one that represents the standby system).
- ClickAdd.
- Type a name in theDevice Namefield.
- Type an external (public) IP address in theAddressfield.
- If you use NAT, type an internal (private) IP address in theTranslationfield.
- ClickAdd. Repeat the steps to add a second device, which represents the standby system.
- ClickOK.
- From theVirtual Server Discoverylist, selectDisabled.
- ClickFinished.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.
- On the Main tab, click.The General configuration screen opens.
- Select theSynchronizecheck box.
- In theGroup Namefield, type the name of the synchronization group.
- In theTime Tolerancefield, type the maximum age difference in seconds, between the sets of configuration files on the systems in a BIG-IP DNS configuration synchronization group.
- Select theSynchronize DNS Zone Filescheck box.
- ClickUpdate.
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.
- On the new BIG-IP DNS system, log in to the command-line interface.
- Typegtm_add, and press Enter.
- Press the y key to start thegtm_addscript.
- 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.