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 re solver 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.
-n nameserver The nameserver to be used in the query. Nameservers can ap pear 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 type 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 class 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 retry The number of times to retry if the nameserver is not re sponding. (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 re solver'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. 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 ordi narily a nameserver only has a list of root nameservers for class IN re source records. 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., 18.104.22.168.5). 4th Berkeley Distribution March 10, 1990 2
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