DNSQUERY

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
FILES
SEE ALSO
DIAGNOSTICS
BUGS
AUTHOR

NAME

dnsquery - query domain name servers using resolver

SYNOPSIS

dnsquery [-n nameserver] [-t type] [-c class] [-r retry] [-p retry period] [-d] [-s] [-v] host

DESCRIPTION

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 ns are treated without case-sensitivity.

OPTIONS

-n

The nameserver to be used in the query. Nameservers can appear as either Internet addresses of the form w.x.y.z or can appear as domain names. (default: as specified in /etc/resolv.conf)

-t

The type of resource record of interest. Types include:

A

address

NS

nameserver

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

ANY

wildcard

Note that any case may be used. (default: ANY)

-c

The class of resource records of interest. Classes include:

IN

Internet

HS

Hesiod

CHAOS

Chaos

ANY

wildcard

Note that any case may be used. (default: IN)

-r

The number of times to retry if the nameserver is not responding. (default: 4)

-p

Period to wait before timing out. (default: RES_TIMEOUT) options field. (default: any answer)

-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)

-v

Synonym for the ’s’ flag.

host

The name of the host (or domain) of interest.

FILES

/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

SEE ALSO

nslookup(@SYS_OPS_EXT@), nstest(@CMD_EXT@), nsquery(@CMD_EXT@), named(@SYS_OPS_EXT@), resolver(@FORMAT_EXT@)

DIAGNOSTICS

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.

BUGS

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 resource records.

Query 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) addresses (e.g. 1.2.3.4.5).

AUTHOR

Bryan Beecher