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Configuration file for named
/etc/named.conf
BIND 8 is much more configurable than previous release of BIND. There are new areas of configuration, such as access control lists and categorized logging, and many options that previously applied to all zones can now be used selectively. These features, plus a consideration of future configuration needs, led to the creation of a new configuration file format.
| This section: | Contains: |
| Documentation definitions | A description of the elements that are used throughout the named configuration file documentation |
| Statements | Elements that are associated with only one statement |
| Comments | Syntax rules for comments |
address_match_list = 1*address_match_element
address_match_element = [ "!" ] (
ip_address /
ip_prefix /
acl_name /
address_match_list)
An address_match_list is a list of elements. The elements can be any of the following:
The ACLs any, none, localhost and localnets are predefined. For more information, see the description of the acl statement.
You can use a leading "!" to negate elements.
When a given IP address or prefix is compared to an address match list, the list is traversed in order, and the first match (regardless of negation) is used. The interpretation of a match depends on whether the list is being used for access control or as a topology.
When used as an ACL, a nonnegated match allows access and a negated match denies access. If there's no match, access is denied. The clauses: allow-query, allow-transfer, and allow-update all use address match lists like this. Similarly, the listen-on clause can use negation to define local addresses that shouldn't be used to accept nameserver connections.
When used with the topology option, a nonnegated match returns a distance based on its position on the list (the closer the match is to the start of the list, the shorter the distance is between it and the server). A negated match is assigned the maximum distance from the server. If there's no match, the address gets a distance that's further than any nonnegated list element, and closer than any negated element.
Because of the first-match aspect of the algorithm, an element that defines a subset of another element in the list should come before the broader element, regardless of whether either is negated. For example, in:
1.2.3/24; ! 1.2.3.13
the 1.2.3.13 element is completely useless because the algorithm matches any lookup for 1.2.3.13 to the 1.2.3/24 element. Using:
! 1.2.3.13; 1.2.3/24
fixes that problem by having 1.2.3.13 blocked by the negation but all other 1.2.3.* hosts fall through.
The maximum value of size_spec is that of unsigned long integers on the machine. The word unlimited requests unlimited use, or the maximum available amount. The word default uses the limit that was in force when the server was started.
A number can optionally be followed by a scaling factor: K or k for kilobytes, M or m for megabytes, and G or g for gigabytes, which scale by 1024, 1024*1024, and 1024*1024*1024, respectively.
Integer storage overflow is currently silently ignored during conversion of scaled values, resulting in values less than intended, possibly even negative. Using unlimited is the best way to safely set a very large number.
A named configuration consists of statements and comments. Statements end with a semicolon. Many statements contain a block of substatements, which are also terminated with a semicolon. The following statements are supported:
The logging and options statements may occur only once per configuration.
acl name {
address_match_list
};
The acl statement creates a named address match list. It gets its name from a primary use of address match lists: Access Control Lists (ACLs).
 |
You must use the acl statement to define the name of an address match list before you can use it elsewhere; no forward references are allowed. |
The following ACLs are builtin:
controls {
[ inet ip_addr
port ip_port
allow { address_match_list; }; ]
};
The controls statement declares control channels to be used by system administrators to affect the operation of the local name server.
An inet control channel is a TCP/IP socket accessible to the Internet, created at the specified ip_port on the specified ip_addr. Modern telnet clients are capable of speaking directly to these sockets, and the control protocol is ARPAnet-style text. It's recommended that 127.0.0.1 be the only ip_addr used, and this only if you trust all nonprivileged users on the local host to manage your name server.
To use this interface with telnet, specify:
telnet ip_addr ip_port
When connected:
Ctrl-]
toggle crlf
>help
Or:
Specifying -noexpired tells the name server not to bother you with error messages about zones that have expired. This comes in handy if your name server is authoritative for thousands of zones and you want to avoid seeing a flurry of expiration messages that you already know about.
Or:
Or:
Specifying higher debug levels increases the amount of detail in the debugging information.
include path_name;
The include statement inserts the specified file at the point that the include statement is encountered. It can't be used within another statement, so the following isn't allowed:
acl internal_hosts { include "internal_hosts.acl" }
Use include to break the configuration up into easily-managed chunks. For example the following could be used at the top of a BIND configuration file in order to include any ACL or key information:
include "/etc/security/keys.bind" include "/etc/acls.bind"
|
Be careful not to type "#include" as you would in a C program, because # is used to start a comment. |
key key_id {
algorithm algorithm_id;
secret secret_string;
};
The key statement defines a key ID that can be used in a server statement to associate an authentication method with a particular name server.
A key ID must be created with the key statement before it can be used in a server definition or an address match list.
The arguments are as follows:
The key statement is intended for use in transaction security. Unless included in a server statement, it's not used to sign any requests. It's used to verify requests matching the key_id and algorithm_id, and sign replies to those requests.
logging {
[ channel channel_name {
( file path_name
[ versions ( number | unlimited ) ]
[ size size_spec ]
| syslog ( kern | user | mail | daemon | auth | syslog | lpr |
news | uucp | cron | authpriv | ftp |
local0 | local1 | local2 | local3 |
local4 | local5 | local6 | local7 )
| null );
[ severity ( critical | error | warning | notice |
info | debug [level] | dynamic ); ]
[ print-category yes_or_no; ]
[ print-severity yes_or_no; ]
[ print-time yes_or_no; ]
}; ]
[ category category_name {
channel_name; [ channel_name; ... ]
}; ]
...
};
The logging statement configures a wide variety of logging options for the nameserver. Its channel phrase associates output methods, format options and severity levels with a name that can then be used with the category phrase to select how various classes of messages are logged.
Sections in this description include:
Only one logging statement is used to define as many channels and categories as are wanted. If there are multiple logging statements in a configuration, the first defined determines the logging, and warnings are issued for the others. If there's no logging statement, the logging configuration is:
logging { category default { default_syslog; default_debug; };
category panic { default_syslog; default_stderr; };
category packet { default_debug; };
category eventlib { default_debug; };
};
The logging configuration is established as soon as the logging statement is parsed. If you want to redirect messages about processing of the entire configuration file, the logging statement must appear first. Even if you do not redirect configuration file parsing messages, we recommend always putting the logging statement first so that this rule needn't be consciously recalled if you ever do want the parser's messages relocated.
All log output goes to one or more "channels." You can make as many of them as you want.
Every channel definition must include a clause that says whether messages selected for the channel go to a file, to a particular syslog() facility, or are discarded. Also, it can optionally limit the message severity level that's accepted by the channel (the default is info), and whether to include a named-generated time stamp, the category name and/or severity level (the default is not to include any).
The word NULL as the destination option for the channel causes all messages sent to it to be discarded; other options for the channel are meaningless.
The file clause can include limitations both on how large the file is allowed to become, and how many versions of the file are saved each time the file is opened.
The size option for files is simply a hard ceiling on log growth. If the file ever exceeds the size, then named just doesn't write anything more to it until the file is reopened; exceeding the size doesn't automatically trigger a reopen. The default behavior is to not limit the size of the file.
If you use the versions logfile option, then named retains that many backup versions of the file by renaming them when opening. For example, if you choose to keep three old versions of the file lamers.log then just before it's opened lamers.log.1 is renamed to lames.log.2, lamers.log.0 is renamed to lamers.log.1, and lamers.log is renamed to lamers.log.0. No rolled versions are kept by default. The unlimited keyword is synonymous with 99 in current releases.
Example usage of the size and versions options:
channel an_example_level {
file "lamers.log" versions 3 size 20m;
print-time yes;
print-category yes;
};
The argument for the syslog clause is a syslog() facility as described for syslog(). In order to capture the log messages, you need to have syslogd running.
The severity clause works like syslog()'s "priorities," except that they can also be used if you are writing straight to a file rather than using syslog(). Messages that aren't at least of the severity level given aren't selected for the channel; messages of higher severity levels are accepted.
If you're using syslog(), the /etc/syslog.conf priorities also determines what eventually passes through. For example, defining a channel facility and severity as daemon and debug but only logging daemon.warning via /etc/syslog.conf causes messages of severity info and notice to be dropped. If the situation were reversed, with named writing messages of only warning or higher, then syslogd would print all messages it received from the channel.
The server can supply extensive debugging information when it's in debugging mode. If the server's global debug level is greater than zero, then debugging mode is active. The global debug level is set either by starting the server with the -d flag followed by a positive integer, or by sending the server the SIGUSR1 signal. The global debug level can be set to zero, and debugging mode turned off, by sending the server the SIGUSR2 signal. All debugging messages in the server have a debug level, and higher debug levels give more more detailed output. Channels that specify a specific debug severity, for example:
channel specific_debug_level {
file "foo";
severity debug 3;
};
gets debugging output of level 3 or less any time the server is in debugging mode, regardless of the global debugging level. Channels with dynamic severity use the server's global level to determine what messages to print.
If print-time has been turned on, then the date and time are logged. It may also be specified for a syslog() channel, but is usually pointless since syslog() also prints the date and time. If print-category is requested, then the category of the message is logged as well. Finally, if print-severity is on, then the severity level of the message is logged.
The print- options may be used in any combination, and are always printed in the following order: time, category, severity.
Here's an example where all three print- options are on:
28-Apr-1997 15:05:32.863 default: notice: Ready to answer queries.
There are four predefined channels that are used for named's default logging as follows. How they are used is described in the next section, the category phrase.
channel default_syslog {
syslog daemon; # send to syslog()'s daemon facility
severity info; # only send priority info and higher
};
channel default_debug {
file "named.run"; # write to named.run in the working directory
# Note: stderr is used instead of named.run
# if the server is started with the -f option.
severity dynamic; # log at the server's current debug level
};
channel default_stderr { # writes to stderr
file "<stderr>"; # this is illustrative only; there's currently
# no way of specifying an internal file
# descriptor in the configuration language.
severity info; # only send priority info and higher
};
channel null {
null; # toss anything sent to this channel
};
Once a channel is defined, it can't be redefined. Thus you can't alter the builtin channels directly, but you can modify the default logging by pointing categories at channels you have defined.
There are many categories, so you can send the logs you want to see wherever you want, without seeing logs you don't want.
The following categories are available:
category default { default_syslog; default_debug; };
category eventlib { default_debug; };
category packet { default_debug; };
category panic { default_syslog; default_stderr; };
If you don't specify a list of channels for a category, then log messages in that category are sent to the default category instead. If you don't specify a default category, the following "default default" is used:
category default { default_syslog; default_debug; };
As an example, let's say you want to log security events to a file, but you also want keep the default logging behavior. You'd specify the following:
channel my_security_channel {
file "my_security_file";
severity info;
};
category security { my_security_channel; default_syslog; default_debug; };
To discard all messages in a category, specify the null channel:
category lame-servers { null; };
category cname { null; };
options {
[ version version_string; ]
[ directory path_name; ]
[ named-xfer path_name; ]
[ dump-file path_name; ]
[ memstatistics-file path_name; ]
[ pid-file path_name; ]
[ statistics-file path_name; ]
[ auth-nxdomain yes_or_no; ]
[ deallocate-on-exit yes_or_no; ]
[ dialup yes_or_no; ]
[ fake-iquery yes_or_no; ]
[ fetch-glue yes_or_no; ]
[ has-old-clients yes_or_no; ]
[ host-statistics yes_or_no; ]
[ multiple-cnames yes_or_no; ]
[ notify yes_or_no; ]
[ recursion yes_or_no; ]
[ rfc2308-type1 yes_or_no; ]
[ use-id-pool yes_or_no; ]
[ treat-cr-as-space yes_or_no; ]
[ also-notify { ip_addr; [ ip_addr; ... ] }; ]
[ forward ( only | first ); ]
[ forwarders { [ ip_addr; [ip_addr; ... ] ] }; ]
[ check-names (master|slave|response) (warn|fail|ignore); ]
[ allow-query { address_match_list }; ]
[ allow-transfer { address_match_list }; ]
[ allow-recursion { address_match_list }; ]
[ blackhole { address_match_list }; ]
[ listen-on [ port ip_port ] { address_match_list }; ]
[ query-source [ address (ip_addr|*) ] [ port (ip_port|*) ] ; ]
[ lame-ttl number; ]
[ max-transfer-time-in number; ]
[ max-ncache-ttl number; ]
[ min-roots number; ]
[ serial-queries number; ]
[ transfer-format ( one-answer | many-answers ); ]
[ transfers-in number; ]
[ transfers-out number; ]
[ transfers-per-ns number; ]
[ transfer-source ip_addr; ]
[ maintain-ixfr-base yes_or_no; ]
[ max-ixfr-log-size number; ]
[ coresize size_spec; ]
[ datasize size_spec; ]
[ files size_spec; ]
[ stacksize size_spec; ]
[ cleaning-interval number; ]
[ heartbeat-interval number; ]
[ interface-interval number; ]
[ statistics-interval number; ]
[ topology { address_match_list }; ]
[ sortlist { address_match_list }; ]
[ rrset-order { order_spec ; [ order_spec ; ... ] ] };
};
The options statement sets up global options to be used by named. This statement may appear only once in a configuration file; if more than one occurrence is found, the first occurrence determines the actual options used, and a warning is generated. If there's no options statement, an options block with each option set to its default is used.
Sections in this description include:
The following options are available:
The following options are available:
If the zone is a master zone, the server sends out a NOTIFY request to all the slaves. This triggers the "zone up to date checking" in the slave (providing it supports NOTIFY), allowing the slave to verify the zone while the call us up.
If the zone is a slave or stub zone, the server suppresses the regular "zone up to date" queries and only perform them when the heartbeat-interval expires.
The use of has-old-clients with auth-nxdomain, maintain-ixfr-base and rfc2308-type1 is order-dependant.
The forwarding facility can be used to create a large site-wide cache on a few servers, reducing traffic over links to external nameservers. It can also be used to allow queries by servers that don't have direct access to the Internet, but wish to look up exterior names anyway. Forwarding occurs only on those queries for which the server isn't authoritative and doesn't have the answer in its cache.
Forwarding options include:
Forwarding can also be configured on a per-zone basis, allowing for the global forwarding options to be overridden in a variety of ways. You can set particular zones to use different forwarders, or have different forward only/first behavior, or to not forward at all. See the zone statement for more information.
Future versions of BIND 8 will provide a more powerful forwarding system. The syntax described above should continue to be supported.
The server can check domain names based upon their expected client contexts. For example, a domain name used as a hostname can be checked for compliance with the RFCs defining valid hostnames.
Three checking methods are available:
The server can check names in three areas: master zone files, slave zone files, and in responses to queries the server has initiated. If check-names response fail has been specified, and answering the client's question would require sending an invalid name to the client, the server sends a REFUSED response code to the client.
The defaults are:
check-names master fail;
check-names slave warn;
check-names response ignore;
The check-names option may also be specified in the zone statement, in which case it overrides the options check-names statement. When used in a zone statement, the area isn't specified (because it can be deduced from the zone type).
Access to the server can be restricted based on the IP address of the requesting system. See address_match_list for details on how to specify IP address lists.
The access control options are:
You can specify the interfaces and ports that the server answer queries from by using the listen-on option, which takes an optional port and an address_match_list. The server listens on all interfaces allowed by the address match list. If a port isn't specified, port 53 is used.
Multiple listen-on clauses are allowed. For example:
listen-on { 5.6.7.8; };
listen-on port 1234 { !1.2.3.4; 1.2/16; };
If no listen-on is specified, the server listens on port 53 on all interfaces.
If the server doesn't know the answer to a question, it queries other nameservers. The query-source option specifies the address and port used for such queries. If address is * or is omitted, a wildcard IP address (INADDR_ANY) is used. If port is * or is omitted, a random unprivileged port is used. The default is:
query-source address * port *;
|
The query-source option currently applies only to UDP queries; TCP queries always use a wildcard IP address and a random unprivileged port. |
The following options are available:
If a server loads a large (tens or hundreds of thousands) number of slave zones, this limit should be raised to the high hundreds or low thousands -- otherwise the slave server may never actually become aware of zone changes in the master servers. Beware, though, that setting this limit arbitrarily high can spend a considerable amount of your slave server's network, CPU, and memory resources. As with all tunable limits, this one should be changed gently and monitored for its effects.
The transfer-format option may be overridden on a per-server basis by using the server statement.
The server's usage of many system resources can be limited. Some operating systems don't support some of the limits. On such systems, a warning will be issued if the unsupported limit is used. Some operating systems don't support limiting resources, and on these systems a "cannot set resource limits on this system" message is logged.
Scaled values are allowed when specifying resource limits. For example, 1G can be used instead of 1073741824 to specify a limit of one gigabyte. unlimited requests unlimited use, or the maximum available amount. default uses the limit that was in force when the server was started. See size_spec for more details.
On some operating systems the server can't set an unlimited value and can't determine the maximum number of open files the kernel can support. On such systems, choosing unlimited causes the server to use the larger of the rlim_max for RLIMIT_NOFILE and the value returned by sysconf(_SC_OPEN_MAX). If the actual kernel limit is larger than this value, use limit files to specify the limit explicitly.
The following options are available:
All other things being equal, when the server chooses a nameserver to query from a list of nameservers, it prefers the one that is topologically closest to itself. The topology option takes an address_match_list and interprets it in a special way. Each top-level list element is assigned a distance. Nonnegated elements get a distance based on their position in the list, where the closer the match is to the start of the list, the shorter the distance is between it and the server. A negated match is assigned the maximum distance from the server. If there's no match, the address gets a distance that's further than any nonnegated list element, and closer than any negated element. For example,
topology {
10/8;
!1.2.3/24;
{ 1.2/16; 3/8; };
};
prefers servers on network 10 the most, followed by hosts on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the exception of hosts on network 1.2.3 (netmask 255.255.255.0), which is preferred least of all.
The default topology is:
topology { localhost; localnets; };
When returning multiple RRs, the nameserver normally returns them in Round Robin -- after each request, the first RR is put to the end of the list. As the order of RRs isn't defined, this shouldn't cause any problems.
The client resolver code should rearrange the RRs as appropriate -- using any addresses on the local net in preference to other addresses. However, not all resolvers can do this, or aren't correctly configured.
When a client is using a local server, the sorting can be performed in the server, based on the client's address. This only requires configuring the nameservers, not all the clients.
The sortlist option takes an address match list and interprets it even more specially than the topology option does.
Each top level statement in the sortlist must itself be an explicit address match list with one or two elements. The first element (which may be an IP address, an IP prefix, an ACL name or nested address match list) of each top level list is checked against the source address of the query until a match is found.
Once the source address of the query has been matched, if the top level statement contains only one element, the actual primitive element that matched the source address is used to select the address in the response to move to the beginning of the response. If the statement is a list of two elements, the second element is treated like the address match list in a topology option. Each top level element is assigned a distance and the address in the response with the minimum distance is moved to the beginning of the response.
In the following example, any queries received from any of the addresses of the host itself will get responses preferring addresses on any of the locally connected networks. Next most preferred are addresses on the 192.168.1/24 network, and after that either the 192.168.2/24 or 192.168.3/24 network with no preference shown between these two networks. Queries received from a host on the 192.168.1/24 network will prefer other addresses on that network to the 192.168.2/24 and 192.168.3/24 networks. Queries received from a host on the 192.168.4/24 or the 192.168.5/24 network will only prefer other addresses on their directly connected networks.
sortlist {
{ localhost; // IF the local host
{ localnets; // THEN first fit on the
192.168.1/24; // following nets
{ 192,168.2/24; 192.168.3/24; }; }; };
{ 192.168.1/24; // IF on class C 192.168.1
{ 192.168.1/24; // THEN use .1, or .2 or .3
{ 192.168.2/24; 192.168.3/24; }; }; };
{ 192.168.2/24; // IF on class C 192.168.2
{ 192.168.2/24; // THEN use .2, or .1 or .3
{ 192.168.1/24; 192.168.3/24; }; }; };
{ 192.168.3/24; // IF on class C 192.168.3
{ 192.168.3/24; // THEN use .3, or .1 or .2
{ 192.168.1/24; 192.168.2/24; }; }; };
{ { 192.168.4/24; 192.168.5/24; }; // if .4 or .5, prefer that net
};
};
The following example gives reasonable behaviour for the local host and hosts on directly connected networks. It's similar to the behavior of the address sort in BIND 4.9.x. Responses sent to:
sortlist {
{ localhost; localnets; };
{ localnets; };
};
When multiple records are returned in an answer it may be useful to configure the order the records are placed into the response. For example the records for a zone might be configured to always be returned in the order they are defined in the zone file. Or perhaps a random shuffle of the records as they are returned is wanted. The rrset-order statement permits configuration of the ordering made of the records in a multiple record response. The default, if no ordering is defined, is a cyclic ordering (round robin).
An order_spec is defined as follows:
[ class class_name ][ type type_name ][ name "FQDN" ] order ordering
| If this option isn't specified: | the default is: |
| class | ANY |
| type | ANY |
| name | "*" |
The legal values for ordering are:
In the following example, any responses for type A records in class IN that have rc.vix.com as a suffix, are always returned in random order. All other records are returned in cyclic order.
rrset-order {
class IN type A name "rc.vix.com" order random;
order cyclic;
};
If multiple rrset-order statements appear, they're not combined -- the last one applies.
If no rrset-order statement is specified, the following is used as the default:
rrset-order { class ANY type ANY name "*" order cyclic ; };
The following options are available:
server ip_addr {
[ bogus yes_or_no; ]
[ support-ixfr yes_or_no; ]
[ transfers number; ]
[ transfer-format ( one-answer | many-answers ); ]
[ keys { key_id [key_id ... ] }; ]
};
The server statement defines the characteristics to be associated with a remote name server.
If you discover that a server is giving out bad data, marking it as bogus prevents further queries to it. The default value of bogus is no.
The server supports two zone transfer methods:
Although this option is more efficient, it's understood only by this release of named.
You specify the method to use for a server with the transfer-format clause. If transfer-format isn't specified, then transfer-format (specified by the options statement) is used.
The transfers clause will be used in a future release of the server to limit the number of concurrent in-bound zone transfers from the specified server. It's checked for syntax but is otherwise ignored.
The keys clause is used to identify a key_id defined by the key statement, to be used for transaction security when talking to the remote server. The key statement must come before the server statement that references it. When a request is sent to the remote server, a request signature is generated using the key specified here and appended to the message. A request originating from the remote server isn't required to be signed by this key.
zone domain_name [ ( in | hs | hesiod | chaos ) ] {
type master;
file path_name;
[ forward ( only | first ); ]
[ forwarders { [ ip_addr ; [ ip_addr ; ... ] ] }; ]
[ check-names ( warn | fail | ignore ); ]
[ allow-update { address_match_list }; ]
[ allow-query { address_match_list }; ]
[ allow-transfer { address_match_list }; ]
[ dialup yes_or_no; ]
[ notify yes_or_no; ]
[ also-notify { ip_addr; [ ip_addr; ... ] }; ]
[ ixfr-base path_name; ]
};
zone domain_name [ ( in | hs | hesiod | chaos ) ] {
type ( slave | stub );
[ file path_name; ]
[ ixfr-base path_name; ]
masters [ port ip_port ] { ip_addr; [ ip_addr; ... ] };
[ forward ( only | first ); ]
[ forwarders { [ ip_addr ; [ ip_addr ; ... ] ] }; ]
[ check-names ( warn | fail | ignore ); ]
[ allow-update { address_match_list }; ]
[ allow-query { address_match_list }; ]
[ allow-transfer { address_match_list }; ]
[ transfer-source ip_addr; ]
[ dialup yes_or_no; ]
[ max-transfer-time-in number; ]
[ notify yes_or_no; ]
[ also-notify { ip_addr; [ ip_addr; ... ] };
};
zone domain_name [ ( in | hs | hesiod | chaos ) ] {
type forward;
[ forward ( only | first ); ]
[ forwarders { [ ip_addr ; [ ip_addr ; ... ] ] }; ]
[ check-names ( warn | fail | ignore ); ]
};
zone "." [ ( in | hs | hesiod | chaos ) ] {
type hint;
file path_name;
[ check-names ( warn | fail | ignore ); ]
};
Sections in this description include:
The following types are available:
If a port is specified, it checks to see if the zone is current, and if so, zone transfers are done to the port given.
If file is specified, then the replica is written to the file. We recommend using file since it often speeds server startup and eliminates a needless waste of bandwidth.
Note that for large numbers (in the tens or hundreds of thousands) of zones per server, it's best to use a two level naming scheme for zone file names. For example, a slave server for the zone vix.com might place the zone contents into a file called vi/vix.com where vi/ is just the first two letters of the zone name. (Most operating systems behave very slowly if you put 100K files into a single directory.)
If either no forwarders clause is present in the zone or an empty list for forwarders is given, no forwarding is done for the zone, cancelling the effects of any forwarders in the options statement. Thus if you want to use this type of zone to change the behavior of the global forward option, and not the servers used, you also need to respecify the global forwarders.
|
Previous releases of named used the term primary for a master zone, secondary for a slave zone, and cache for a hint zone. |
The zone's name may optionally be followed by one of the following classes:
The following options are available for zone:
/* This is a comment as in C */ // This is a comment as in C++ # This is a comment as in common Unix shells and perl
Comments may appear anywhere that whitespace may appear in a named configuration file.
C-style comments start with the two characters /* (slash, star) and end with */ (star, slash). Because they are completely delimited with these characters, they can be used to comment a portion of a line or to span multiple lines.
C-style comments can't be nested. For example, the following isn't valid because the entire comment ends with the first */:
/* This is the start of a comment. This is still part of the comment. /* This is an incorrect attempt at nesting a comment. */ This is no longer in any comment. */
C++-style comments start with the two characters // (slash, slash) and continue to the end of the physical line. They can't be continued across multiple physical lines; to have one logical comment span multiple lines, each line must use the // pair. For example:
// This is the start of a comment. The next line // is a new comment, even though it's logically // part of the previous comment.
Shell-style (or perl-style, if you prefer) comments start with the pound sign (#) and continue to the end of the physical line, like C++ comments. For example:
# This is the start of a comment. The next line # is a new comment, even though it's logically # part of the previous comment.
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You can't use a semicolon (;) to start a comment such as you would in a zone file. The semicolon indicates the end of a configuration statement, so whatever follows it is interpreted as the start of the next statement. |
syslogd() in the Library Reference
TCP/IP Network Administration
DNS and BIND by Paul Albitz and Cricket Liu, O'Reilly & Associates (ISBN 1-56592-010-4)
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