nslookup(8)						      System Manager's Manual						       nslookup(8)

NAME

       nslookup - Queries Internet name servers interactively

SYNOPSIS

       nslookup [-option ...] [host-to-find |- [server]]

DESCRIPTION

       The  nslookup command is a program that is used to query Internet domain name servers.  The nslookup command has two modes: interactive and
       noninteractive.	Noninteractive mode is used to print just the name and requested information for a host or domain.  Noninteractive mode is
       invoked	when  the name or Internet address of the host to be looked up is given as the first argument. The optional second argument speci-
       fies the hostname or address of a name server.  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.  Interactive mode is invoked when you specify nslookup without arguments (the default
       name server will be used), or when the first argument you specify is a - (dash) and the second argument is the hostname or Internet address
       of a name server.

       The  options  listed under the set command 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 - (dash).	 For  example,	to
       change the default query type to host information, and the initial time-out to 10 seconds, enter: nslookup -query=hinfo	-timeout=10

   Interactive Commands
       Commands may be interrupted at any time by entering <Ctrl-c>.  To exit, enter <Ctrl-d> (EOF) or type exit.  The command line length must be
       less than 256 characters.  To treat a built-in command as a hostname, precede it with an escape character    (backslash).   Note  that	an
       unrecognized command will be interpreted as a hostname.

       Looks  up information for host using the current default server or using server if specified.  If host is an Internet address and the query
       type is A or PTR, the name of the host is returned.  If host 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 set options domain, srchlist, defname, and search).  To look up a host not
       in the current domain, append a . (dot) to the name.  Changes the default server to domain.  lserver uses the initial  server  to  look	up
       information  about  domain, while server uses the current default server.  If an authoritative answer cannot be found, the names of servers
       that might have the answer are returned.  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 synonym for lserver ns.internic.net.)  The name of the root server can be changed with
       the set root command.  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 set querytype=A command).  name is optional.  The> and >> (redirection symbols)
       can be used to redirect output in the usual manner.  Lists the information available for domain, optionally creating or appending to  file-
       name.   The  default  output contains hostnames and their Internet addresses.  option can be one of the following: Lists all records of the
       specified type (see querytype later in this reference page).  Lists aliases of hosts in the domain.  This option is a synonym for -t CNAME.
       Lists  all  records for the domain.  This option is a synonym for -t ANY.  Lists CPU and operating system information for the domain.  This
       option is a synonym for -t HINFO.  Lists well-known services of hosts in the domain.  This option is a synonym for -t WKS.  When output	is
       directed  to a file, # (number signs) are printed for every 50 records received from the server.  Sorts and lists the output of previous ls
       command(s) with more.  Prints a brief summary of commands.  Exits the program.  This command is	used  to  change  state  information  that
       affects	the lookups.  Valid keywords are: Prints the current values of the frequently used options to set.  Information about the  current
       default server and host is also printed.  Changes the query class to one of: The Internet class.  The Chaos class.  The MIT  Athena  Hesiod
       class.	Wildcard  (any of the above).  The class specifies the protocol group of the information.  (Default = IN, abbreviation = cl) Turns
       debugging mode on. A lot more information is printed about the packet sent to the server and the resulting  answer.   (Default  =  nodebug,
       abbreviation  = [no]deb) Turns exhaustive debugging mode on.  Essentially all fields of every packet are printed.  (Default = nod2) Changes
       the default domain name to name.  The default domain name is appended to a lookup request depending on the state of the defname and  search
       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 set srchlist command to specify a dif-
       ferent list.  Use the set all command to display the list.  (Default = value from hostname, /etc/resolv.conf or LOCALDOMAIN, abbreviation =
       do) Changes the default domain name to name1 and the domain search list to name1, name2, and so on. A maximum of 6  names  separated  by  /
       (slashes)  can be specified: For example: set srchlist=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU sets the domain to lcs.MIT.EDU and the search list to
       the three names.  This command overrides the default domain name and search list of the set domain command.  Use the  set  all  command	to
       display	the  list.  (Default = value based on hostname, /etc/resolv.conf or LOCALDOMAIN, abbreviation = srchl) If set, appends the default
       domain name to a single-component lookup request (that is, one that does not contain a dot).  (Default = defname, abbreviation  =  [no]def)
       If  the	lookup	request  contains at least one . (dot) but does not end with a trailing dot, appends the domain names in the domain search
       list to the request until an answer is received.  (Default = search, abbreviation = [no]sea) Changes the default TCP/UDP name  server  port
       to  value.   (Default  =  53, abbreviation = po) Changes the type of information query to one of: The host's IPv4 address.  The host's IPv6
       address.  The canonical name for an alias.  The host CPU and operating system type.  The  mailbox  or  mail  list  information.	 The  mail
       exchanger.  The Naming AUthority PoinTeR that contains rules for mapping parts of Uniform Resource Identifiers (URIs) to domain names.  The
       name server for the named zone.	The hostname if the query is an Internet  address;  otherwise  the  pointer  to  other	information.   The
       domain's  start-of-authority information.  The host that can provide a specific resolution service.  The text information.  The user infor-
       mation.	The supported well-known services.  Other types (ANY, AXFR, MB, MD, MF, NULL) are described in the RFC1035 document.   (Default  =
       A,  abbreviations = q, ty) Tells the name server to query other servers if it does not have the information.  (Default = recurse, abbrevia-
       tion = [no]rec) Sets the number of retries to number.  When a reply to a request is not received within a certain amount of  time  (changed
       with  set  time-out), the timeout period is doubled and the request is resent.  The retry value controls how many times a request is resent
       before giving up.  (Default = 4, abbreviation = ret) Changes the name of the root server to host. This affects the root command.   (Default
       =  ns.internic.net., abbreviation = ro) Changes the initial timeout interval for waiting for a reply to number seconds.	Each retry doubles
       the timeout period.  (Default = 5 seconds, abbreviation = ti) Always use a virtual circuit when sending requests to the server.	(Default =
       novc, abbreviation = [no]v) Ignore packet truncation errors.  (Default = noignoretc, abbreviation = [no]ig)

EXIT VALUES

       In noninteractive mode, nslookup can return the following values: A match was found.  No match was found, or an error occurred.

ERRORS

       If  the lookup request was not successful, an error message is printed.	Possible errors are: The server did not respond to a request after
       a certain amount of time (changed with set timeout=value) and a certain number of retries (changed with set retry=value).  No  name  server
       is  running on the server machine.  The server does not have resource records of the current query type for the host, although the hostname
       is valid.  The query type is specified with the set querytype command.  The host or domain name does not exist.	The connection to the name
       or  finger server could not be made at the current time.  This error commonly occurs with ls and finger requests.  The name server found an
       internal inconsistency in its database and could not return a valid answer.  The name server refused to	service  the  request.	 The  name
       server found that the request packet was not in the proper format.  It may indicate an error in nslookup.

FILES

       Specifies the command path Initial domain name and name server addresses User's initial options Summary of commands

RELATED INFORMATION

       Commands: named(8)

       Functions: resolver(4)

       Files: resolv.conf(4)

       Specifications:	RFC1034, RFC1035 delim off

																       nslookup(8)