Manual Chapter :
Configuring a TTL in a DNS NoError Response
Applies To:
Show Versions
BIG-IP LTM
- 17.0.0, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0
BIG-IP DNS
- 17.0.0, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0
Configuring a TTL in a DNS NoError Response
Overview: Configuring a TTL in a DNS NoError Response
You can configure BIG-IP DNS to return DNS NoError responses that include a TTL. With this configuration, local DNS servers can cache a negative response. Negative caching reduces both the response time for negative DNS responses and the number of messages that must be sent between resolvers and local DNS servers.
About SOA records and negative caching
A start of authority (SOA) record contains a TTL by which a local DNS server can be configured to cache a Return Code On Failure to a query
Create a wide IP that provides for negative caching
Ensure that at least one global load balancing pool exists in the configuration before you create a wide IP.
Create a wide IP configured in a manner where BIG-IP DNS returns an SOA record that contains a TTL with an IPv6 DNS NoError response. With this configuration, the local DNS servers can cache a negative response and thus provide faster responses to DNS queries.
- On the Main tab, click .The Wide IP List screen opens.
- ClickCreate.The New Wide IP List screen opens.
- From the General Properties list, selectAdvanced.
- In theNamefield, type a name for the wide IP.You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
- From theTypelist, select a record type for the wide IP.Once created, both the record type and name cannot be changed.
- From theNoError Responselist, selectEnabled.With this option enabled, the system responds faster to requests for which it does not have AAAA records configured.
- In theNoError TTLfield, type the number of seconds that the local DNS servers consider the NoError response to be valid. When you set this value, you must enable theNoError Responsesetting as well.
- In the Pools area, for thePool Listsetting, select the pools that this wide IP uses for load balancing.The system evaluates the pools based on the wide IP load balancing method configured.
- From thePoollist, select a pool.A pool can belong to more than one wide IP.
- ClickAdd.
- ClickFinished.
Create a load balancing pool
Ensure that at least one virtual server exists in the configuration before you start to create a load balancing pool for global traffic.
- On the Main tab, click .The Pools list screen opens.
- ClickCreate.The New Pool screen opens.
- In the General Properties area, in theNamefield, type a name for the pool.Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.The pool name is limited to 63 characters.
- From theTypelist, depending on the type of the system (IPv4 or IPv6), select either anAorAAAApool type.
- In the Configuration area, for theHealth Monitorssetting, in theAvailablelist, select a monitor type, and move the monitor to theSelectedlist.Hold the Shift or Ctrl key to select more than one monitor at a time.
- In the Members area, for theMember Listsetting, add virtual servers as members of this load balancing pool.The system evaluates the virtual servers (pool members) in the order in which they are listed. A virtual server can belong to more than one pool.
- Select a virtual server from theVirtual Serverlist.
- ClickAdd.
- ClickFinished.
