You can configure BIG-IP® DNS to return a start of authority (SOA) Negative Caching time-to-live (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.
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.
You can configure DNS to provide a negative caching TTL for a domain name by performing these specific tasks.
|NAPTR||The Name Authority Pointer record, NAPTR, aids in the standardization of Uniform Resource Names (URNs). NAPTR records map between sets of URNs, URLs and plain domain names, and suggest to clients the protocols available for communication with the mapped resource.|
|A||The Address record, or A record, lists the IP address for a given host name.|
|SRV||The Service resource record, SRV, is a pointer with which an alias for a given service is redirected to another domain.|
|CNAME||The Canonical Name resource record, CNAME, specifies an alias or nickname for the official, or canonical, host name.|
|AAAA||The IPv6 Address record, or AAAA record, lists the 128-bit IPv6 address for a given host name.|
|MX||The Mail Exchange resource record, MX, defines the mail system(s) for a given domain.|
|NOERROR (No Error)||No error condition.|
|FORMERR (Query Format Error)||The name server was unable to interpret the query.|
|SERVFAIL (Server Failure)||The name server was unable to process this query due to a problem with the name server.|
|NXDOMAIN (Non Existent Domain)||The domain name referenced in the query does not exist.|
|NOTIMP (Not Implemented)||The name server does not support the requested kind of query.|
|REFUSED (Refuse To Answer)||The name server refuses to perform the specified operation for policy reasons.|
You now have an implementation in which DNS returns a TTL in a Return Code On Failure for a web site represented by a wide IP in the BIG-IP DNS configuration.