nslookup

nslookup

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Diagnostic utility that displays information stored in DNS servers.

Modes

nslookup has two modes of operation:

Interactive

In this mode, an nslookup shell is opened so that any sequence of nslookup commands can be run one at a time. Enter interactive mode by typing:

  nslookup  

Noninteractive

In this mode, only a single nslookup command is run, after which you return to the command prompt. The syntax is:

 nslookup -   command host DNSserver   

-command

One of the nslookup commands in the following list. The hyphen is part of the syntax.

host

The IP address or hostname of the host whose DNS information you want to obtain from the DNS server. If you use a hyphen, the prompt changes to nslookup interactive mode.

DNSserver

The IP address or hostname of the DNS server you want to query. (If omitted, the default DNS server for the local machine is used.)

Commands

exit

Quits the interactive mode of nslookup .

finger [username]

Fingers the current computer for a list of currently logged-on users. If you specify username, then the information for that user is obtained.

ls [option] dnsdomain [[> >>] filename]

Lists (or redirects to a file) different subsets of resource records for the specified DNS domain depending on the option selected, specifically :

-t querytype

Lists all records of the specified type (see Table 5-22)

-a

Lists aliases of hosts in the DNS domain (same result as using -t CNAME )

-d

Lists all records for the DNS domain (same result as using -t ANY )

-h

Lists operating-system information for the DNS domain (same result as using -t HINFO )

-s

Lists well-known services of host in the DNS domain (same result as using -t WKS )

lserver dnsdomain

Sets the default server to the specified DNS domain using the initial server.

root

Sets the default server to the DNS root server ns.nic.ddn.mil (same result as using lserver ns.nic.ddn.mil ). Use set root to change the default root server.

server dnsdomain

Sets the default server to the specified DNS domain using the current default server.

set all

Displays the configuration of nslookup (how it performs lookups).

set class=value

Modifies the query class, which can be IN (Internet class), CHAOS (Chaos class), HESIOD (MIT Athena Hesiod class), or ANY (any class). The default is IN (the other classes are obsolete).

set [no]d2

Enables or disables exhaustive debugging mode, which is incredibly verbose (default is no ).

set [no]debug

Enables or disables debugging mode, which is very verbose (default is no ).

set [no]defname

Appends the default DNS domain name to each query (default is yes ).

set domain= dnsdomain

Switches the default DNS domain to the one specified. This name is appended to all nslookup queries if defname is specified.

set [no]ignore

Reports or ignores packet errors (default is ignore ).

set port=value

Modifies the default TCP/UDP port for the DNS name server port. (This is port 53 by default.)

set querytype=value

Specifies the types of resource records to obtain from the DNS server (see Table 5-22). The default is Address (A) record.

set [no]recurse

Enables or disables recursion, i.e.,whether the DNS server should query other DNS servers if it can't respond with the requested information. (Default is yes .)

set retry =number

Specifies the number of retries that can be performed by nslookup when querying a DNS server until it gives up (default is four times).

set root=DNSserver

Specifies the root server (affects the root command earlier in this list). The default is ns.nic.ddn.mil .

set [no]search

Toggles whether each DNS domain name in the search list should be appended to a request until a response is received (default is yes).

set srchlist DNSdomain1[/DNSdomain2/...]

Specifies the DNS domain name search list (up to six DNS servers can be specified).

set timeout=seconds

Modifies the initial time in seconds that nslookup waits for a response to its first request (default is five seconds).

set type=value

Specifies the type of records to be requested from a DNS server (see Table 5-22).

set [no]vc

Specifies that a virtual circuit should be used when sending requests to a DNS server (default is no ).

view filename

Displays the output of any previous commands that have been redirected to files.

Table 5-22. Values for querytype parameter for nslookup commands

Value	Description
A	Computer's IP address
ANY	All types of data
CNAME	Canonical name for an alias
GID	Group identifier of a group name
HINFO	Computer's CPU and operating-system type
MB	Mailbox domain name
MG	Mail group member
MINFO	Mailbox or mail-list information
MR	Mail rename domain name
MX	Mail exchanger
NS	DNS name server for the named zone
PTR	Hostname (if the query is an IP address) or pointer to other info
SOA	DNS domain's start-of-authority record
TXT	Text information
UID	User identifier
UINFO	User information
WKS	Well-known service description

Examples

Start nslookup in interactive mode:

 C:\>  nslookup  Default Server:  izzy.mtitworld.com Address:  172.16.11.99 > 

Switch default DNS server to BACH :

 >  server bach.mtitworld.com  Default Server:  bach.mtitworld.com Address:  172.16.11.100 

Specify that only Address (A) records should be queried:

 >  set query=A  

Resolve host BEETHOVEN in domain mtitworld.com into its IP address:

 >  beethoven.mtitworld.com  Server:  bach.mtitworld.com Address:  172.16.11.100 Name:    beethoven.mtitworld.com Address:  172.16.11.101 

Query default DNS server for all records in its database:

 >  ls mtitworld.com  [bach.mtitworld.com]  mtitworld.com.                 A      172.16.11.100  mtitworld.com.       NS     server=bach.mtitworld.com  gc._msdcs                      A      172.16.11.105  gc._msdcs                      A      172.16.11.103  gc._msdcs                      A      172.16.11.104  gc._msdcs                      A      172.16.11.100  bach                           A      172.16.11.100  beethoven                      A      172.16.11.101  chopin                         A      172.16.11.102  distrib                        A      172.16.11.103  franck.distrib                 A      172.16.11.103  handel                         A      172.16.11.70  chopin.vancouver               A      172.16.11.102 

Notes

• nslookup commands must be 255 or fewer characters .

• To look up a computer not in the current DNS domain, append a period to the name. For example, type beethoven.otherdomain.com. at the interactive nslookup prompt.

• Use exit or Ctrl-C to escape from an nslookup session.

• An unrecognized command is interpreted as a hostname.

• For more information on using nslookup , see DNS on Windows Server 2003 (O'Reilly).

See Also

DNS