To add a new server and enable the BIND resolver, enter:

TCPIP> SET NAME_SERVICE /SERVER=host /ENABLE /SYSTEM

For host, specify the host name or IP address of the BIND server or servers that the BIND resolver will query.

To specify multiple hosts, list them by request preference. The BIND resolver sends the first lookup request to the first host on the list.

If you define a server list and then add a new server with the SET NAME_SERVICE /SERVER command, the new server is added to the end of the list.

SET commands affect the volatile database. To save your changes to the permanent database, enter SET CONFIGURATION commands. The changes you make with the SET CONFIGURATION commands take effect the next time the software starts up. For example, enter:

TCPIP> SET CONFIGURATION NAME_SERVICE /SERVER=host /ENABLE

TCPIP> SHOW CONFIGURATION NAME_SERVICE BIND Resolver Configuration Transport: UDP Domain: ucx.ern.sea.com Retry: 4 Timeout: 4 Servers: 9.20.208.47, 9.20.208.53 Path: No values defined

5.8.2 Examples

The following command defines hosts PARROT, SORA, and JACANA as systemwide BIND servers and enables the BIND resolver:

PARROT> TCPIP TCPIP> SET NAME_SERVICE /SERVER=(PARROT,SORA,JACANA) /SYSTEM /ENABLE

The following example defines, for the current login session, host OSPREY as the BIND server. As a result, the servers that are defined systemwide will not be queried.

TCPIP> SET NAME_SERVICE /SERVER=OSPREY

5.8.3 Resolver Default Search Behavior

By default, if no search list is defined and the host name as you typed it has no dot (.) in the name, the BIND resolver performs a lookup as follows:

1. On the host name, with the default domain appended
2. Just the host name

For example, if you enter the command:

$TCPIP SHOW HOST OWL

assuming that the default domain is ucx.ern.sea.com, the resolver performs lookups as follows:

1. On the host name and domain owl.ucx.ern.sea.com
2. If that lookup is unsuccessful, the resolver searches for host owl.

This behavior is different than the resolver lookup behavior in previous releases (UCX BIND Version 4.x.). The following section provides more information.

5.8.4 Resolver Search Behavior in Earlier Releases

In previous releases the resolver performs lookups as follows:

• Appends the default domain to the host name and performs a lookup.
• If the previous lookup fails, the resolver removes the leftmost label from the default domain name, appends the result to the host name and performs the lookup.
• If that lookup fails, the resolver again removes the leftmost label from the default domain name, appends the result to the host name, and performs the lookup.

For each unsuccessful lookup, this procedure is reiterated until only two labels remain in the resulting domain name.

If all the above attempts fail, the resolver tries just the host name as typed in (as long as it contains at least one dot).

For example, if you enter the command:

$TCPIP SHOW HOST OWL

assuming the default domain is ucx.ern.sea.com, the resolver performs lookups as follows:

• On owl.ucx.ern.sea.com
• If the previous lookup was unsuccessful, the resolver searches for owl.ern.sea.com.
• If that lookup was unsuccessful, the resolver searches for owl.sea.com.
• Finally, if the last lookup was unsuccessful, the resolver searched for owl.

The search list is provided to make entering lookup commands easier by not having to type in fully qualified host/domain names. The search list consists of domain names that the resolver uses when performing lookups. By default, the search list consists of only the default domain, which is stored in TCPIP$CONFIGURATION.DAT.

You can change the elements in the search list by entering the SET NAME_SERVICE command as shown in the following example:

$TCPIP>SET NAME_SERVICE /PATH=(ucx.ern.sea.com,dux.sea.com,mux.ern.sea.com) /SYSTEM

For example, if you enter the command:

$TCPIP SHOW HOST CANARY

The resolver performs lookups as follows:

1. On canary.ucx.ern.sea.com
2. If the previous lookup is unsuccessful, the resolver searches canary.dux.sea.com.
3. If that lookup is unsuccessful, the resolver searches canary.mux.ern.sea.com.
4. If that lookup is unsuccessful, the resolver searches canary.

The PATH: label in the SHOW NAME command output shows the search list information entered with the SET NAME /PATH command. This command displays system-wide information and process-specific information (if process-specific information is set).

$ TCPIP SHOW NAME BIND Resolver Parameters Local domain: ucx.ern.sea.com System State: Started, Enabled Transport: UDP Domain: ucx.ern.sea.com Retry: 4 Timeout: 4 Servers: ucx, lemng, 16.99.0.10 Path: ucx.ern.sea.com,dux.ern.sea.com,mux.ern.sea.com Process State: Enabled Transport: Domain: Retry: Timeout: Servers: Path: $

Any additions you make are appended to the end of the search list.

To remove an element from the search list, enter the following command:

$TCPIP> SET NAME_SERVICE /NOPATH=dux.ern.sea.com /SYSTEM

NSLOOKUP is a debugging tool provided with BIND that allows anyone to directly query a name server and retrieve information. Use NSLOOKUP to determine if your local name server is running correctly or to retrieve information from remote servers.

NSLOOKUP makes direct queries to name servers around the world to obtain DNS information, which includes:

• Host names and addresses on the local domain
• Host names and addresses on remote domains
• Host names that serve as mail exchangers (MX records)
• Name servers for a specific zone

Table 5-12 shows how to start and stop NSLOOKUP.

Table 5-12 NSLOOKUP Options

Action	Type This...
Run NSLOOKUP	$ RUN SYS$SYSTEM:TCPIP$NSLOOKUP.EXE
Terminate NSLOOKUP from within interactive mode	> exit
Terminate the current NSLOOKUP session	> Ctrl/z
Display online help	> HELP

To run NSLOOKUP as a foreign command, enter the following command at the $ prompt or place the command in your login.com file:

$NSLOOKUP :== $SYS$SYSTEM:TCPIP$NSLOOKUP.EXE

You can then run an interactive NSLOOKUP session by entering:

$NSLOOKUP >

You can put NSLOOKUP set commands in an initialization file, SYS$LOGIN:NSLOOKUPINIT.INI. The commands are executed when you start NSLOOKUP.

5.9.2 Obtaining Help

• Entering the following DCL HELP command:

  $HELP TCPIP_SERVICES NSLOOKUP

• Entering one of the following NSLOOKUP help commands:

  >?

  
  or

  >help

The following example shows the information available with the NSLOOKUP Help (?) command:

$ nslookup Default Server: condor.lgk.dec.com Address: 16.99.208.53 > ? Information available: <host> About_nslookup exit finger ls lserver root server set Topic?

5.9.3 NSLOOKUP Commands

NSLOOKUP interprets unrecognized commands as host names. When using NSLOOKUP, apply these syntax rules:

• The command line must be fewer than 256 characters.
• Commands must be either uppercase or lowercase. NSLOOKUP does not accept commands in mixed case.

When NSLOOKUP first starts, you see the name and address of the default BIND server, followed by the NSLOOKUP prompt. In the following example, the default server is condor.lgk.dec.com.

$ nslookup Default Server: condor.lgk.dec.com Address: 16.99.208.53 >

Table 5-13 lists the NSLOOKUP commands.

Table 5-13 NSLOOKUP Commands

Command	Function
host [ server ]	Looks up information using the current default server or the server you specify. Enter the name of the host for which you need an IP address. For example, the following command searches for www.whitehouse.gov using the the default server: > www.whitehouse.gov Server: condor.lgk.dec.com Address: 16.99.208.53 Name: www.whitehouse.gov Addresses: 198.137.240.92, 198.137.240.91 The following command uses the server with IP address 128.45.45.40 to look up the host snowy.frozen.weather.com: > snowy.frozen.weather.com 128.45.45.40
server domain	Changes the default server to the domain you specify. The following command changes the default server using the current default server to look up information for the new default server, 128.45.35.40: > server 128.45.35.40
lserver domain	Changes the default server. The following command changes the default server using the current default server to find information about 128.45.35.40: > lserver 128.45.35.40
root	Changes the default server to the server specified by the root option. > root
ls	Lists information about hosts in the domain you specify. The default output contains host names and their IP addresses. The options for ls are listed in Table 5-15. The following example redirects the output from the screen to the file nslookup.temp in the current directory. > ls -a frozen.weather.com > nslookup.temp
help or ?	Prints a summary of the available commands.
exit	Exits NSLOOKUP.
set	Selects the type of information that NSLOOKUP displays. Table 5-14 lists the available options.

5.9.4 Default Option Values

NSLOOKUP has options that influence the type of information you receive from a query and the way NSLOOKUP behaves. Some of the options take a value and others are boolean options. The options have default values and can be changed by using the set command.

You obtain a list of the options and their default values by entering the set all command immediately after starting an interactive NSLOOKUP session, as shown in the following example:

$ nslookup Default Server: condor.lgk.dec.com (1) Address: 16.99.208.53 > set all (2) Default Server: condor.lgk.dec.com Address: 16.99.208.53 Set options: nodebug defname search recurse (3) nod2 novc noignoretc port=53 (4) querytype=A (5) class=IN timeout=4 retry=4 root=a.root-servers.net. domain=xyz.prq.dec.com (6) srchlist=xyz.prq.dec.com (7) >

1. The current default name server. This option is initially set to the name server configured for your local system (client).
2. The set all command displays the current value of each option. When NSLOOKUP starts, it initializes the options with default values. If you enter the set all command immediately after starting up NSLOOKUP, you will see the default values.
3. Boolean options are those that have an on/off state. Boolean options that are in the off state are prefixed with the character string NO. For example, nodebug.
4. NSLOOKUP displays options that take a value with an equal sign (=) and the option's current value. For example, port=53.
5. The querytype option specifies the type of information returned on a query. The default query type is A, which returns the host's IP address.
6. The domain option specifies a default domain. When you query with a host name, the default domain is appended to the host name before issuing the query. The defname and search options affect how NSLOOKUP appends the default domain name.
7. The srchlist option specifies 1 to 6 domains to search by default. NSLOOKUP sets the domain option to the first domain listed in the search list.

For a description of other set options, see Table 5-14.

Table 5-14 Options to the NSLOOKUP set Command

Option	Function
ALL	Prints the current values of the options you can set as well as information about the current default server. For example: > set type=all
class= value	Changes the query class to one of the following: IN --- The Internet class (default) CHAOS --- The Chaos class ANY --- Wildcard The class specifies the protocol group of the information. You can use the abbreviated form of the keyword cl. This command tells NSLOOKUP to resolve both internet and chaos class queries (you can enter INTERNET and CHAOS): > set class=ANY
querytype	Specifies the type of information you want. For example: > set querytype=A > set querytype=ANY Valid types include: SOA Start of Authority. Marks the beginning of a zone's data and defines parameters that affect the entire zone. NS Name Server. Identifies a domain's name server. A Address. Maps a host name to an address. ANY Defines all available resource records for a given name. PTR Pointer. Maps an address to a host name. MX Identifies where to deliver mail for a given domain. CNAME Defines an alias host name. HINFO Host Information. Describes a host's hardware and OS. WKS Well-known service. Advertises network services.
[no]debug	Turns on debugging (default is nodebug). NSLOOKUP prints verbose information about the packet sent to the server and the answer. You can use the abbreviations nodeb and deb. For example: > set debug
[no]d2	Returns all-inclusive debugging information (default is nod2 ). Prints all the fields of every packet. For example: > set d2
recurse	Tells the BIND server to contact other servers if it does not have the information you want. The servers carry out a complete (recursive) resolution for each query. For example: > set recurse
retry	Number of times that NSLOOKUP attempts to contact a BIND server if repeated tries fail. For example: > set retry=8
timeout	Length of time to wait for a reply from each attempt. For example: > set timeout=9
root= value	Changes the root server. For example, the following command changes the root server to ns.nasa.gov. > set root=ns.nasa.gov
ignoretc	Tells NSLOOKUP to ignore packet truncation errors. For example: > set ignoretc
domain name	Changes the default domain to the domain you specify. How the default domain name is appended to look up requests depends on the settings 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. The default value is set in the TCP/IP configuration database. To specify the default, type the abbreviation do. For example, if the default domain is CC.Berkeley.EDU, the search list is CC.Berkeley.EDU and Berkeley.EDU.
srchlist	IF set, NSLOOKUP will append each of the domain names specified in the srchlist option to an unqualified host name and perform a query until an answer is received.
srchlist= names	Changes the default domain name to the first name you specify and the domain search list to all the names you specify. Specify a maximum of six names separated by slashes (/). In the following example, the command sets the default domain to lcs.MIT.EDU and the search list to the three specified domains. The command overrides the default domain name and associated search list for the set domain command. > set srchlist=lcs.MIT.EDU/ai.MIT.EDU/MIT.EDU The default is the domain name specified in the TCP/IP configuration database. The abbreviated form of the command is srchl.
[no]defname	Tells NSLOOKUP to append a default domain name to a not fully qualified 2 DNS name lookup request. The abbreviated form is [no]def. For example, an NSLOOKUP query for the host rainy becomes rainy.cc.berkeley.edu.
[no]search	Tells NSLOOKUP to append the domain names in the search list to a not fully qualified domain name 2 lookup request. The default is search. The abbreviated form is [no]sea.