query Internet name servers interactively
nslookup [options...] [host | [-server]]
- options
- Any of the options listed in the ``set command keywords''
section below may 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, you would enter:
nslookup -query=hinfo -timeout=10
- host
- Look up information for host using the
current default server.
- server
- Look up information using this server.
The nslookup utility lets you query Internet
domain name servers. The utility has two modes: interactive
and non-interactive. In interactive mode, you can query
name servers for information about various hosts and domains
or print a list of hosts in a domain. In non-interactive mode,
nslookup just prints the name and requested information
for a host or domain.
|
The nslookup utility won't look at /etc/hosts
even if the lookup keyword is used in /etc/resolv.conf. |
The utility enters interactive mode when:
- no arguments are given (the default name server is used)
OR
- the first argument is a hyphen (-) and the
second argument is the hostname or Internet address of a name server.
The utility enters non-interactive mode when the first
argument is the name or Internet address of the host to be
looked up. The optional second argument specifies the host
name or address of a name server.
The options listed under the ``set command keywords''
section may be specified in the .nslookuprc file in
your home directory, where they should be listed one per line.
To interrupt a command at any time, press
Ctrl
-C
. To exit,
press
Ctrl
-D
(EOF)
or type exit. To treat a builtin command as a host
name, place an escape character (\) before the
command.
Note that the length of the command line must be less than
256 characters.
|
Any unrecognized command will be interpreted as a hostname. |
- exit
- Exit the utility.
- finger [name] [> filename]
finger [name] [>> filename]
- Connect with the finger server on the current host. The
current host is defined when a previous lookup for a host
completed successfully and returned address information (see
the set querytype=A command). The
name argument is optional. Note that you can use
> and >> in the usual manner.
- help
?
- Print a brief summary of commands.
- ls [option] domain [> filename]
ls [option] domain [>> filename]
- List the information available for domain,
optionally creating or appending to filename. If
no option is given, the output contains hostnames and their
Internet addresses. The option argument can be
one of the following:
- -a
- List aliases of hosts in the domain. Synonym for -t CNAME.
- -d
- List all records for the domain. Synonym for -t ANY.
- -h
- List CPU and OS information for the domain. Synonym
for -t HINFO.
- -s
- List well-known services of hosts in the domain. Synonym
for -t WKS. When output is directed to a
file, hash marks are printed for every 50 records received
from the server.
- -t querytype
- List all records of the specified type (see querytype below).
- root
- Change the default server to the server for the root of
the domain namespace. Because the host
ns.nic.ddn.mil is currently used, this
command is a synonym for
lserver ns.nic.ddn.mil. You
can change the name of the root server with the
set root command.
- set keyword[=value]
- Change state information that affects the lookups.
See the set command keywords section for details
on the set command.
- server domain
lserver domain
- Change the default server to domain. The
lserver form uses the initial server to look up
information about domain while server
uses the current default server. If an authoritative answer
can't be found, the names of servers that might have the
answer are returned.
- view filename
- Sort and list the output of previous ls
commands with more.
- all
- Print the current values of set's most
frequently used options as well as information about the
current default server and host.
- class=value
- The class specifies the protocol group of the information
(default is IN, abbreviation is cl).
Change the query class to one of:
- ANY
- Query for any of the following.
- CHAOS
- Chaos class.
- HESIOD
- MIT Athena Hesiod class.
- IN
- Internet class.
- [no]d2
- Turn exhaustive debugging mode on. All fields of
every packet are printed (default is nod2).
- [no]debug
- Turn debugging mode on. A lot more information is
printed about the packet sent to the server and the
resulting answer (default is nodebug,
abbreviation is [no]deb).
- [no]defname
- Append the default domain name to a single-component
lookup request; i.e. one that doesn't contain a period
(default is defname, abbreviation is [no]def).
- domain=name
- Change 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 (see below).
The domain search list contains the parents of the default
domain if the domain 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 (default
is the value from hostname, /etc/resolv.conf.<nid>
/etc/resolv.conf file, or LOCALDOMAIN environment variable;
abbreviation is do).
To specify a different list, use set srchlist
(see below); to display the list, use set all.
- [no]ignoretc
- Ignore packet truncation errors (default is noignoretc,
abbreviation is [no]ig)
- port=value
- Change the default TCP/UDP name server port to
value (default is 53, abbreviation is po).
- querytype=value
type=value
- 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 OS type.
- MINFO
- The mailbox, or mail-list information.
- MX
- The mail exchanger.
- NS
- The name server for the named zone.
- PTR
- The hostname 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.
The types (ANY, AXFR, MB, MD,
MF, NULL) are described in the RFC 1035 document.
Default is A; abbreviations are q, ty.
- [no]recurse
- Tell the name server to query other servers if it
doesn't have the information (default is recurse,
abbreviation is [no]rec).
- retry=number
- Set the number of retries to number. When a
reply to a request isn't received within a certain amount of
time (changed with set timeout), the timeout period is
doubled and the request is sent again. The number
argument controls how many times a request is resent before
nslookup gives up (default is 4, abbreviation is ret).
- root=host
- Change the name of the root server to
host. This affects the root command (default is
ns.nic.ddn.mil., abbreviation is ro).
- [no]search
- 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 is search, abbreviation is [no]sea).
- srchlist=name1/name2/...
- Change the default domain name to name1 and
the domain search list to name1,
name2, etc. (default is the value based on hostname,
/etc/resolv.conf.<nid>
/etc/resolv.conf file, or
LOCALDOMAIN environment variable;
abbreviation is srchl).
You can specify a maximum of six names separated by slashes
(/). For example, this command:
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.
- timeout=number
- Change the initial timeout interval for waiting for a
reply to the specified number of seconds. Each retry doubles
the timeout period (default is 5, abbreviation is ti)
- [no]vc
- Always use a virtual circuit when sending requests to
the server (default is novc, abbreviation is [no]v)
If the lookup request wasn't successful, one of the
following error messages may be printed:
- Connection refused - Network is unreachable
- The connection to the name or finger server couldn't be
made at the current time. This error commonly occurs with
ls and finger requests.
- Format error
- The name server found that the request packet wasn't in
the proper format. This may indicate an error in
nslookup.
- No records
- The server doesn't 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.
- No response from server
- No name server is running on the server machine.
- Non-existent domain
- The hostname or domain name doesn't exist.
- Refused
- The name server refused to service the request.
- Server failure
- The name server found an internal inconsistency in its
database and couldn't return a valid answer.
- Timed out
- The server didn't 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).
- /etc/resolv.conf.<nid>
- Initial domain name and name server addresses. If /etc/resolv.conf.<nid>
exists then /etc/resolv.conf will be ignored.
- $HOME/.nslookuprc
- User's initial options.
- /etc/nslookup.help
- Summary of commands.
- HOSTALIASES
- Contains host aliases.
- LOCALDOMAIN
- Overrides default domain.
named
RFC 1034, RFC 1035