Documentation

Shape of a typed lookup: a Resolver and a query Domain produce either a list of answers, or a DNSError. An empty list means that either the name exists and has no records of the queried type (NODATA), or the name does not exist (NXDOMAIN). Both are non-error outcomes.

Given a DNSMessage return answer RRs that match its question, possibly after chasing CNAME aliases within the answer section of the message.

Perform a raw lookup with per-call QueryControls overrides, returning the full DNSMessage or a DNSError. The supplied controls are merged into the resolver's ambient query controls: only the flag and EDNS bits specified in the controls affect the outgoing query, the rest are inherited from the resolver configuration. Use lookupAnswers (or the per-RRtype Lookup functions) when you want only the answer RRs for the requested name and type, rather than the entire response DNSMessage.

Perform a raw lookup returning the full DNSMessage or a DNSError. See lookupRawCtl for the variant that takes per-call query controls.

Perform the requested query and return the answer RRs from the response, or a DNSError carrying the RCODE for error responses. The QueryControls argument carries per-call tweaks; it is merged onto the resolver's ambient query controls, so callers only need to specify the flag and EDNS bits they want to change, the rest are inherited from the resolver configuration.

Note that NXDOMAIN is not a lookup error. An empty list of RRs is returned for both NODATA and NXDOMAIN.

If the nameserver's response does not include any RRs matching query name and type, but does include a CNAME record for the requested name, the response is (recursively) rescanned for records matching that name and type instead. Note, no additional queries are issued if the final CNAME found does not lead to any record of the desired record type.

The returned RRs may include covering DNSSEC signatures when the DOflag is set as part of the QueryControls, and the response was signed.

The presence of RRSIG records does not however imply that the response was validated by the resolver. For that one would typically use a trusted DNSSEC-validating local (loopback) resolver, to which the network path is immune to potential active attacks, and inspect the ADflag in the response message.

The full response DNSMessage can be obtained via lookupRawCtl.

Apply an IO action to each lookup value and collect the results. If the the action's first argument is polymorphic, a type application at the call site may be needed to make it possible to determine the type of its argument.

Apply an IO action to each lookup value and discard the results. If the the action's first argument is polymorphic, a type application at the call site may be needed to make it possible to determine the type of its argument.

Generic answer-RData lookup, applying a function to each result. If the the function's first argument is polymorphic, a type application at the call site may be needed to make it possible to determine the type of its argument.

IPv4 addresses of query domain.

IPv6 addresses of query domain.

AFSDB RData of query domain.

CAAs RData of query domain

CDNSKEY RData of query domain.

CDS RData of query domain.

CNAMEs of query domain (should be at most one).

DNAMEs of query domain (should be at most one).

DNSKEY RData of query domain.

DS RData of query domain.

HINFO RData of query domain.

HTTPS RData of query domain.

MX RData of query domain.

Nameservers of query domain.

NSEC RData of query domain.

NSEC3PARAM RData of query domain.

NULL RR payload of query domain.

PTR names of query domain.

RP RData of query domain.

SOA RData of query domain.

SRV RData of query domain.

SSHFP RData of query domain.

SVCB RData of query domain.

TLSA RData of query domain.

TXT RData of query domain. Applications typically concatenate each list of character strings into a single combined value.

ZONEMD RData of query domain.