NAMED(8) UNIX Programmer's Manual NAMED(8) NAME named - Internet domain name server SYNOPSIS named [ -d _d_e_b_u_g_l_e_v_e_l ] [ -p _p_o_r_t# ] [{-b} _b_o_o_t_f_i_l_e ] DESCRIPTION _N_a_m_e_d is the Internet domain name server. See RFC883 for more information on the Internet name-domain system. Without any arguments, _n_a_m_e_d will read the default boot file /_e_t_c/_n_a_m_e_d._b_o_o_t, read any initial data and listen for queries. Options are: -d Print debugging information. A number after the ``d'' determines the level of messages printed. -p Use a different port number. The default is the stan- dard port number as listed in /etc/services. -b Use an alternate boot file. This is optional and allows you to specify a file with a leading dash. Any additional argument is taken as the name of the boot file. The boot file contains information about where the name server is to get its initial data. If multiple boot files are specified, only the last is used. Lines in the boot file cannot be continued on subsequent lines. The fol- lowing is a small example: ; ; boot file for name server ; directory /usr/local/domain ; type domain source host/file backup file cache . root.cache primary Berkeley.EDU berkeley.edu.zone primary 32.128.IN-ADDR.ARPA ucbhosts.rev secondary CC.Berkeley.EDU 128.32.137.8 128.32.137.3 cc.zone.bak secondary 6.32.128.IN-ADDR.ARPA 128.32.137.8 128.32.137.3 cc.rev.bak primary 0.0.127.IN-ADDR.ARPA localhost.rev forwarders 10.0.0.78 10.2.0.78 ; slave The ``directory'' line causes the server to change its work- ing directory to the directory specified. This can be important for the correct processing of $INCLUDE files in primary zone files. Printed 11/26/99 February 28, 1988 1 NAMED(8) UNIX Programmer's Manual NAMED(8) The ``cache'' line specifies that data in ``root.cache'' is to be placed in the backup cache. Its main use is to specify data such as locations of root domain servers. This cache is not used during normal operation, but is used as ``hints'' to find the current root servers. The file ``root.cache'' is in the same format as ``berkeley.edu.zone''. There can be more than one ``cache'' file specified. The cache files are processed in such a way as to preserve the time-to-live's of data dumped out. Data for the root nameservers is kept artificially valid if necessary. The first ``primary'' line states that the file ``berkeley.edu.zone'' contains authoritative data for the ``Berkeley.EDU'' zone. The file ``berkeley.edu.zone'' con- tains data in the master file format described in RFC883. All domain names are relative to the origin, in this case, ``Berkeley.EDU'' (see below for a more detailed descrip- tion). The second ``primary'' line states that the file ``ucbhosts.rev'' contains authoritative data for the domain ``32.128.IN-ADDR.ARPA,'' which is used to translate addresses in network 128.32 to hostnames. Each master file should begin with an SOA record for the zone (see below). The first ``secondary'' line specifies that all authorita- tive data under ``CC.Berkeley.EDU'' is to be transferred from the name server at 128.32.137.8. If the transfer fails it will try 128.32.137.3 and continue trying the addresses, up to 10, listed on this line. The secondary copy is also authoritative for the specified domain. The first non- dotted-quad address on this line will be taken as a filename in which to backup the transfered zone. The name server will load the zone from this backup file if it exists when it boots, providing a complete copy even if the master servers are unreachable. Whenever a new copy of the domain is received by automatic zone transfer from one of the mas- ter servers, this file will be updated. The second ``secon- dary'' line states that the address-to-hostname mapping for the subnet 128.32.136 should be obtained from the same list of master servers as the previous zone. The ``forwarders'' line specifies the addresses of sitewide servers that will accept recursive queries from other servers. If the boot file specifies one or more forwarders, then the server will send all queries for data not in the cache to the forwarders first. Each forwarder will be asked in turn until an answer is returned or the list is exhausted. If no answer is forthcoming from a forwarder, the server will continue as it would have without the for- warders line unless it is in ``slave'' mode. The forwarding facility is useful to cause a large sitewide cache to be generated on a master, and to reduce traffic over links to Printed 11/26/99 February 28, 1988 2 NAMED(8) UNIX Programmer's Manual NAMED(8) outside servers. It can also be used to allow servers to run that do not have access directly to the Internet, but wish to act as though they do. The ``slave'' line (shown commented out) is used to put the server in slave mode. In this mode, the server will only make queries to forwarders. This option is normally used on machine that wish to run a server but for physical or admin- istrative reasons cannot be given access to the Internet, but have access to a host that does have access. The ``sortlist'' line can be used to indicate networks that are to be preferred over other, unlisted networks. Queries for host addresses from hosts on the same network as the server will receive responses with local network addresses listed first, then addresses on the sort list, then other addresses. This line is only acted on at initial startup. When reloading the nameserver with a SIGHUP, this line will be ignored. The master file consists of control information and a list of resource records for objects in the zone of the forms: $INCLUDE $ORIGIN where _d_o_m_a_i_n is "." for root, "@" for the current origin, or a standard domain name. If _d_o_m_a_i_n is a standard domain name that does not end with ``.'', the current origin is appended to the domain. Domain names ending with ``.'' are unmodi- fied. The _o_p_t__d_o_m_a_i_n field is used to define an origin for the data in an included file. It is equivalent to placing a $ORIGIN statement before the first line of the included file. The field is optional. Neither the _o_p_t__d_o_m_a_i_n field nor $ORIGIN statements in the included file modify the current origin for this file. The _o_p_t__t_t_l field is an optional integer number for the time-to-live field. It defaults to zero, meaning the minimum value specified in the SOA record for the zone. The _o_p_t__c_l_a_s_s field is the object address type; currently only one type is supported, IN, for objects connected to the DARPA Internet. The _t_y_p_e field con- tains one of the following tokens; the data expected in the _r_e_s_o_u_r_c_e__r_e_c_o_r_d__d_a_t_a field is in parentheses. A a host address (dotted quad) NS an authoritative name server (domain) MX a mail exchanger (domain) CNAME the canonical name for an alias (domain) Printed 11/26/99 February 28, 1988 3 NAMED(8) UNIX Programmer's Manual NAMED(8) SOA marks the start of a zone of authority (domain of originating host, domain address of maintainer, a serial number and the following parameters in seconds: refresh, retry, expire and minimum TTL (see RFC883)) MB a mailbox domain name (domain) MG a mail group member (domain) MR a mail rename domain name (domain) NULL a null resource record (no format or data) WKS a well know service description (not implemented yet) PTR a domain name pointer (domain) HINFO host information (cpu_type OS_type) MINFO mailbox or mail list information (request_domain error_domain) Resource records normally end at the end of a line, but may be continued across lines between opening and closing parentheses. Comments are introduced by semicolons and con- tinue to the end of the line. Each master zone file should begin with an SOA record for the zone. An example SOA record is as follows: @ IN SOA ucbvax.Berkeley.EDU. rwh.ucbvax.Berkeley.EDU. ( 2.89 ; serial 10800 ; refresh 3600 ; retry 3600000 ; expire 86400 ) ; minimum The SOA lists a serial number, which should be changed each time the master file is changed. Secondary servers check the serial number at intervals specified by the refresh time in seconds; if the serial number changes, a zone transfer will be done to load the new data. If a master server can- not be contacted when a refresh is due, the retry time specifies the interval at which refreshes should be attempted until successful. If a master server cannot be contacted within the interval given by the expire time, all data from the zone is discarded by secondary servers. The minimum value is the time-to-live used by records in the file with no explicit time-to-live value. Printed 11/26/99 February 28, 1988 4 NAMED(8) UNIX Programmer's Manual NAMED(8) NOTES The boot file directives ``domain'' and ``suffixes'' have been obsoleted by a more useful resolver based implementa- tion of suffixing for partially qualified domain names. The prior mechanisms could fail under a number of situations, especially when then local nameserver did not have complete information. The following signals have the specified effect when sent to the server process using the _k_i_l_l(1) command. SIGHUP Causes server to read named.boot and reload database. SIGINT Dumps current data base and cache to /usr/tmp/named_dump.db SIGIOT Dumps statistics data into /usr/tmp/named.stats if the server is compiled -DSTATS. Statistics data is appended to the file. SIGSYS Dumps the profiling data in /usr/tmp if the server is compiled with profiling (server forks, chdirs and exits). SIGTERM Dumps the primary and secondary database files. Used to save modified data on shutdown if the server is com- piled with dynamic updating enabled. SIGUSR1 Turns on debugging; each SIGUSR1 increments debug level. (SIGEMT on older systems without SIGUSR1) SIGUSR2 Turns off debugging completely. (SIGFPE on older sys- tems without SIGUSR2) FILES /etc/named.boot name server configuration boot file /var/run/named.pid the process id /usr/tmp/named.run debug output /usr/tmp/named_dump.db dump of the name server database /usr/tmp/named.stats nameserver statistics data SEE ALSO kill(1), gethostbyname(3), signal(3), resolver(3), resolver(5), hostname(7), RFC882, RFC883, RFC973, RFC974, _N_a_m_e _S_e_r_v_e_r _O_p_e_r_a_t_i_o_n_s _G_u_i_d_e _f_o_r _B_I_N_D Printed 11/26/99 February 28, 1988 5