dnsquery -- query domain name servers using resolver
dnsquery [-n nameserver] [-t type] [-c class] [-r retry] [-p period] [-d]
[-s] [-v] host
The dnsquery program is a general interface to nameservers via BIND
resolver library calls. The program supports queries to the nameserver
with an opcode of QUERY. This program is intended to be a replacement or
supplement to programs like nstest, nsquery and nslookup. All arguments
except for host and nameserver are treated without case-sensitivity.
The nameserver to be used in the query. Nameservers can
appear as either Internet addresses of the form (w.x.y.z or
xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx) or can appear as
domain names. (Default: as specified in /etc/resolv.conf.)
-t type The type of resource record of interest. Types include:
CNAME canonical name
PTR domain name pointer
SOA start of authority
WKS well-known service
HINFO host information
MINFO mailbox information
MX mail exchange
RP responsible person
MG mail group member
AFSDB DCE or AFS server
Note that any case may be used. (Default: ANY.)
-c class The class of resource records of interest. Classes include:
Note that any case may be used. (Default: IN.)
-r retry The number of times to retry if the nameserver is not
responding. (Default: 4.)
-p period Period to wait before timing out. (Default: RES_TIMEOUT.)
-d Turn on debugging. This sets the RES_DEBUG bit of the
resolver's options field. (Default: no debugging.)
-s Use a stream rather than a packet. This uses a TCP stream
connection with the nameserver rather than a UDP datagram.
This sets the RES_USEVC bit of the resolver's options field.
(Default: UDP datagram.)
-v Synonym for the ``-s'' flag.
host The name of the host (or domain) of interest.
/etc/resolv.conf to get the default ns and search lists
<arpa/nameser.h> list of usable RR types and classes
<resolv.h> list of resolver flags
If the resolver fails to answer the query and debugging has not been
turned on, dnsquery will simply print a message like:
Query failed (rc = 1): Unknown host
The value of the return code is supplied by h_errno.
nslookup(8), nstest(1), nsquery(1), named(8), resolver(5).
Queries of a class other than IN can have interesting results since ordinarily
a nameserver only has a list of root nameservers for class IN
Dnsquery uses a call to inet_addr() to determine if the argument for the
``-n'' option is a valid Internet address. Unfortunately, inet_addr()
seems to cause a segmentation fault with some (bad) IP addresses (e.g.,
4th Berkeley Distribution March 10, 1990 4th Berkeley Distribution
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