Manual Chapter : Placing BIG-IP DNS in front of a Pool of DNS Servers

Applies To:

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BIG-IP DNS

  • 14.0.1, 14.0.0

BIG-IP LTM

  • 14.0.1, 14.0.0
Manual Chapter

Placing BIG-IP DNS in front of a Pool of DNS Servers

Overview: Screening and forwarding non-wide IP traffic to a pool of DNS servers

BIG-IP® DNS can function as a traffic screener in front of a pool of DNS servers. In this situation, BIG-IP DNS checks incoming DNS queries and if the query is for a wide IP, resolves the query. Otherwise, BIG-IP DNS forwards the DNS query to one of the servers in a pool of DNS servers, and that server handles the query.
Traffic flow when BIG-IP DNS screens traffic to a pool of DNS servers
Traffic flow when BIG-IP DNS screens traffic to a pool of DNS servers

About listeners

A
listener
is a specialized virtual server that passively checks for DNS packets on port 53 and the IP address you assign to the listener. When a DNS request is sent to the IP address of the listener, the BIG-IP system either handles the request or forwards the request to the appropriate resource.

Placing DNS in front of a pool of DNS servers

Perform these tasks to screen non-wide IP traffic and forward the traffic to a pool of DNS servers.

Creating a pool of local DNS servers

Ensure that at least one custom DNS monitor exists on the BIG-IP system. Gather the IP addresses of the DNS servers that you want to include in a pool to which the BIG-IP system load balances DNS traffic.
Create a pool of local DNS servers when you want to load balance DNS queries to other DNS servers.
  1. On the Main tab, click the applicable path.
    • DNS
      Delivery
      Load Balancing
      Pools
    • Local Traffic
      Pools
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  3. In the
    Name
    field, type a unique name for the pool.
  4. For the
    Health Monitors
    setting, from the
    Available
    list, select the custom DNS monitor you created and move the monitor to the
    Active
    list.
  5. Using the
    New Members
    setting, add each resource that you want to include in the pool:
    1. (Optional) In the
      Node Name
      field, type a name for the node portion of the pool member.
    2. In the
      Address
      field, type an IP address.
    3. In the
      Service Port
      field, type a port number, or select a service name from the list.
    4. (Optional) In the
      Priority
      field, type a priority number.
    5. Click
      Add
      .
  6. Click
    Finished
    .

Creating listeners that alert BIG-IP DNS to DNS queries for a pool of DNS servers

Ensure that a pool of DNS servers exists on DNS.
Configure a listener that alerts BIG-IP DNS to DNS queries destined for a pool of DNS servers. 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 this procedure 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. From the
    Listener
    list, select
    Advanced
    .
  6. For the
    Address Translation
    setting, select the
    Enabled
    check box.
  7. In the Service area, from the
    Protocol
    list, select
    UDP
    .
  8. From the
    Default Pool
    list, select the pool to which this listener forwards DNS queries.
  9. 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.

Implementation result

You now have an implementation in which BIG-IP® DNS receives DNS queries, handles wide IP requests, and forwards all other DNS queries to members of the pool of DNS servers.