4.4BSD/usr/share/man/cat1/nslookup.0
NSLOOKUP(8) BSD System Manager's Manual NSLOOKUP(8)
NNAAMMEE
nslookup - query Internet name servers interactively
SSYYNNOOPPSSIISS
nnssllooookkuupp [ _-_o_p_t_i_o_n _._._. ] [ _h_o_s_t_-_t_o_-_f_i_n_d | - [ _s_e_r_v_e_r ]]
DDEESSCCRRIIPPTTIIOONN
_N_s_l_o_o_k_u_p is a program to query Internet domain name
servers. Nslookup has two modes: interactive and non-
interactive. Interactive mode allows the user to query
name servers for information about various hosts and
domains or to print a list of hosts in a domain. Non-
interactive mode is used to print just the name and
requested information for a host or domain.
AARRGGUUMMEENNTTSS
Interactive mode is entered in the following cases:
a) when no arguments are given (the default name server
will be used),
b) when the first argument is a hyphen (-) and the second
argument is the host name or Internet address of a
name server.
Non-interactive mode is used when the name or Internet
address of the host to be looked up is given as the first
argument. The optional second argument specifies the host
name or address of a name server.
The options listed under the ``set'' command below can be
specified in the .nslookuprc file in the user's home
directory if they are listed one per line. Options can
also be specified on the command line if they precede the
arguments and are prefixed with a hyphen. For example, to
change the default query type to host information, and the
initial timeout to 10 seconds, type:
nslookup -query=hinfo -timeout=10
IINNTTEERRAACCTTIIVVEE CCOOMMMMAANNDDSS
Commands may be interrupted at any time by typing a con
trol-C. To exit, type a control-D (EOF) or type exit.
The command line length must be less than 256 characters.
To treat a built-in command as a host name, precede it
with an escape character (\). NN..BB.. an unrecognized com
mand will be interpreted as a host name.
_h_o_s_t [_s_e_r_v_e_r]
Look up information for _h_o_s_t using the current
default server or using _s_e_r_v_e_r if specified. If
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_h_o_s_t is an Internet address and the query type is A
or PTR, the name of the host is returned. If _h_o_s_t
is a name and does not have a trailing period, the
default domain name is appended to the name. (This
behavior depends on the state of the sseett options
ddoommaaiinn, ssrrcchhlliisstt, ddeeffnnaammee, and sseeaarrcchh). To look up
a host not in the current domain, append a period
to the name.
sseerrvveerr _d_o_m_a_i_n
llsseerrvveerr _d_o_m_a_i_n
Change the default server to _d_o_m_a_i_n. LLsseerrvveerr uses
the initial server to look up information about
_d_o_m_a_i_n while sseerrvveerr uses the current default
server. If an authoritative answer can't be found,
the names of servers that might have the answer are
returned.
rroooott Changes the default server to the server for the
root of the domain name space. Currently, the host
ns.internic.net is used. (This command is a syn
onym for llsseerrvveerr nnss..iinntteerrnniicc..nneett..) The name of the
root server can be changed with the sseett rroooott com
mand.
ffiinnggeerr [_n_a_m_e] [>> _f_i_l_e_n_a_m_e]
ffiinnggeerr [_n_a_m_e] [>>>> _f_i_l_e_n_a_m_e]
Connects with the finger server on the current
host. The current host is defined when a previous
lookup for a host was successful and returned
address information (see the sseett qquueerryyttyyppee==AA com
mand). _N_a_m_e is optional. >> and >>>> can be used to
redirect output in the usual manner.
llss [_o_p_t_i_o_n] _d_o_m_a_i_n [>> _f_i_l_e_n_a_m_e]
llss [_o_p_t_i_o_n] _d_o_m_a_i_n [>>>> _f_i_l_e_n_a_m_e]
List the information available for _d_o_m_a_i_n, option
ally creating or appending to _f_i_l_e_n_a_m_e. The
default output contains host names and their Inter
net addresses. _O_p_t_i_o_n can be one of the following:
--tt _q_u_e_r_y_t_y_p_e
lists all records of the specified type (see
_q_u_e_r_y_t_y_p_e below).
--aa lists aliases of hosts in the domain. synonym
for --tt CCNNAAMMEE.
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--dd lists all records for the domain. synonym for
--tt AANNYY.
--hh lists CPU and operating system information for
the domain. synonym for --tt HHIINNFFOO.
--ss lists well-known services of hosts in the
domain. synonym for --tt WWKKSS.
When output is directed to a file, hash marks are
printed for every 50 records received from the
server.
vviieeww _f_i_l_e_n_a_m_e
Sorts and lists the output of previous llss com
mand(s) with _m_o_r_e(1).
hheellpp
?? Prints a brief summary of commands.
eexxiitt Exits the program.
sseett _k_e_y_w_o_r_d[=_v_a_l_u_e]
This command is used to change state information
that affects the lookups. Valid keywords are:
aallll Prints the current values of the frequently-
used options to sseett. Information about the
current default server and host is also
printed.
ccllaassss==_v_a_l_u_e
Change the query class to one of:
IN the Internet class.
CHAOS the Chaos class.
HESIOD the MIT Athena Hesiod class.
ANY wildcard (any of the above).
The class specifies the protocol group of
the information.
(Default = IN, abbreviation = cl)
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[[nnoo]]ddeebbuugg
Turn debugging mode on. A lot more informa
tion is printed about the packet sent to the
server and the resulting answer.
(Default = nodebug, abbreviation = [no]deb)
[[nnoo]]dd22 Turn exhaustive debugging mode on. Essen
tially all fields of every packet are
printed.
(Default = nod2)
ddoommaaiinn==_n_a_m_e
Change the default domain name to _n_a_m_e. The
default domain name is appended to a lookup
request depending on the state of the ddeeff
nnaammee and sseeaarrcchh options. The domain search
list contains the parents of the default
domain if it has at least two components in
its name. For example, if the default
domain is CC.Berkeley.EDU, the search list
is CC.Berkeley.EDU and Berkeley.EDU. Use
the sseett ssrrcchhlliisstt command to specify a dif
ferent list. Use the sseett aallll command to
display the list.
(Default = value from hostname,
/etc/resolv.conf or LOCALDOMAIN, abbrevia
tion = do)
ssrrcchhlliisstt==_n_a_m_e_1_/_n_a_m_e_2_/_._._.
Change the default domain name to _n_a_m_e_1 and
the domain search list to _n_a_m_e_1, _n_a_m_e_2, etc.
A maximum of 6 names separated by slashes
(/) can be specified. For example,
set srch
list=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU
sets the domain to lcs.MIT.EDU and the
search list to the three names. This com
mand overrides the default domain name and
search list of the sseett ddoommaaiinn command. Use
the sseett aallll command to display the list.
(Default = value based on hostname,
/etc/resolv.conf or LOCALDOMAIN, abbrevia
tion = srchl)
[[nnoo]]ddeeffnnaammee
If set, append the default domain name to a
single-component lookup request (i.e., one
that does not contain a period).
(Default = defname, abbreviation = [no]def)
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[[nnoo]]sseeaarrcchh
If the lookup request contains at least one
period but doesn't end with a trailing
period, append the domain names in the
domain search list to the request until an
answer is received.
(Default = search, abbreviation = [no]sea)
ppoorrtt==_v_a_l_u_e
Change the default TCP/UDP name server port
to _v_a_l_u_e.
(Default = 53, abbreviation = po)
qquueerryyttyyppee==_v_a_l_u_e
ttyyppee==_v_a_l_u_e
Change the type of information query to one
of:
A the host's Internet address.
CNAME the canonical name for an alias.
HINFO the host CPU and operating system
type.
MINFO the mailbox or mail list informa
tion.
MX the mail exchanger.
NS the name server for the named
zone.
PTR the host name if the query is an
Internet address, otherwise the
pointer to other information.
SOA the domain's ``start-of-
authority'' information.
TXT the text information.
UINFO the user information.
WKS the supported well-known services.
Other types (ANY, AXFR, MB, MD, MF, NULL)
are described in the RFC-1035 document.
(Default = A, abbreviations = q, ty)
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[[nnoo]]rreeccuurrssee
Tell the name server to query other servers
if it does not have the information.
(Default = recurse, abbreviation = [no]rec)
rreettrryy==_n_u_m_b_e_r
Set the number of retries to _n_u_m_b_e_r. When a
reply to a request is not received within a
certain amount of time (changed with sseett
ttiimmeeoouutt), the timeout period is doubled and
the request is resent. The retry value con
trols how many times a request is resent
before giving up.
(Default = 4, abbreviation = ret)
rroooott==_h_o_s_t
Change the name of the root server to _h_o_s_t.
This affects the rroooott command.
(Default = ns.internic.net., abbreviation =
ro)
ttiimmeeoouutt==_n_u_m_b_e_r
Change the initial timeout interval for
waiting for a reply to _n_u_m_b_e_r seconds. Each
retry doubles the timeout period.
(Default = 5 seconds, abbreviation = ti)
[[nnoo]]vvcc Always use a virtual circuit when sending
requests to the server.
(Default = novc, abbreviation = [no]v)
[[nnoo]]iiggnnoorreettcc
Ignore packet truncation errors.
(Default = noignoretc, abbreviation =
[no]ig)
DDIIAAGGNNOOSSTTIICCSS
If the lookup request was not successful, an error message
is printed. Possible errors are:
Timed out
The server did not respond to a request after a cer
tain amount of time (changed with sseett ttiimmeeoouutt==_v_a_l_u_e)
and a certain number of retries (changed with sseett
rreettrryy==_v_a_l_u_e).
No response from server
No name server is running on the server machine.
No records
The server does not have resource records of the
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current query type for the host, although the host
name is valid. The query type is specified with the
sseett qquueerryyttyyppee command.
Non-existent domain
The host or domain name does not exist.
Connection refused
Network is unreachable
The connection to the name or finger server could not
be made at the current time. This error commonly
occurs with llss and ffiinnggeerr requests.
Server failure
The name server found an internal inconsistency in
its database and could not return a valid answer.
Refused
The name server refused to service the request.
Format error
The name server found that the request packet was not
in the proper format. It may indicate an error in
_n_s_l_o_o_k_u_p.
FFIILLEESS
/etc/resolv.conf initial domain name and
name server addresses.
$HOME/.nslookuprc user's initial options.
/usr/share/misc/nslookup.help summary of commands.
EENNVVIIRROONNMMEENNTT
HOSTALIASES file containing host aliases.
LOCALDOMAIN overrides default domain.
SSEEEE AALLSSOO
resolver(3), resolver(5), named(8),
RFC-1034 ``Domain Names - Concepts and Facilities''
RFC-1035 ``Domain Names - Implementation and Specifica
tion''
AAUUTTHHOORR
Andrew Cherenson
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