HP-UX Mailing Services Administrator's Guide (B2355-91064)

You must include the -R switch, which specifies the DNS resource record type, to
lookup in the dns map declaration.
Sendmail supports the following types of resource records: A, AAAA, AFSDB, CNAME,
MX, NS, PTR, SRV, and TXT. A map lookup returns only one record. For certain types
of records, such as MX records, the return value can be a random element of the list
because of the randomizing in the DNS resolver.
Table 2-1 describes the different -R values in the dns database map.
Table 2-1 The —R Values in the dns Database Map
Description-R Value
Returns the IPv4 address records for the host (RFC 1035)
A
Returns the IPv6 address records for the host (RFC 1886)
AAAA
Returns an AFS server resource record (RFC 1183)
AFSDB
Returns the canonical name for the host (RFC 1035)
CNAME
Returns the best MX record for the host (RFC 1035)
MX
Returns a name server record (RFC 1035)
NS
Returns the host name that corresponds to an IP record (RFC 1035)
PTR
Returns the port to use for a service (RFC 2782)
SRV
Returns general (human-readable) information (RFC 1035)
TXT
Table 2-2 lists the switches that you can use to make efficient use of the dns
database-map.
Table 2-2 The dns Database-Map Type K Command Switches
DescriptionSwitch
Appends values for duplicate keys.
-A
Appends tag on successful match.
-a
Denotes the res_search()_res.retry interval.-d
Informs Sendmail not to fold keys to lowercase.
-f
Suppresses replacement on match.
-m
Appends a null byte to all keys.
-N
Specifies Sendmail not to add a null byte.
-O
Specifies an optional database map.
-o
Informs Sendmail not to strip quotes from the key.
-q
Modifying the Default Sendmail Configuration File 51