Internet Direct (Indy) Version 9.0.2 Beta
|
TSOARecord = class(TResultRecord)
A Start of Authority resource record is used to identify the start of a zone of authority for the authoritative data in the Answer section of the DNS response. A Start of Authority resource record is especially for describing name server zone management parameters.
A Start of Authority resource record uses the same DNS packet layout as other TResultRecord-based responses, but extends the use of RData to include the following definition and format:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | | . . . MNAME . . . +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | | . . . RNAME . . . +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | SERIAL | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | REFRESH | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | RETRY | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | EXPIRE | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | MINIMUM | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
All times are expressed in seconds.
Most of these fields are pertinent only for name server maintenance operations. However, MINIMUM is used in all query operations that retrieve Resource Records from a zone.
Whenever a Start of Authority RR is sent in a response to a query, the TTL field is set to the maximum of the TTL field from the Resource Record, and the MINIMUM field in the appropriate SOA. Thus MINIMUM is a lower bound on the TTL field for all RRs in a zone. Note that this use of MINIMUM should occur when the Resource Records are copied into the response and not when the zone is loaded from a master file or via a zone transfer. The reason for this provison is to allow future dynamic update facilities to change the Start of Authority Resource Record with known semantics.
TSOARecord extends TResultRecord to implement the specifics of accessing RData values as properties, including Primary, ResponsiblePerson, Serial, Refresh, Retry, Expire, and MinimumTTL. TSOARecord also overrides the Parse method to read the values in RData into their property counterparts.