The Configuration File etcnamed.boot

Note The names of the zone files could be different for some real system. They are always explicitly specified in etcnamed.boot etcnamed.conf file. Here listed names sound logical, but they are arbitrary and will be used in the text that follows for educational purposes only.

16.3.1 BIND Version 4.X.X

We will discuss named configuration by having in mind earlier BIND releases — up to version 4. Such an approach is sufficiently general, and all differences introduced by newer BIND releases actually they start with version 8 will be completely covered in later sections.

16.3.1.1 The Configuration File etcnamed.boot

Let us start with an arbitrary example for the secondary server: cat etcnamed.boot ;−−−−−−−−−−−−−−−−−−etcnamed.boot−−−−−−−−−−−−−−−−−−−−− ; directory varnamedxferd ; ;type domain source host file ; secondary myschool.scps.edu 146.98.1.12 named.hosts secondary 98.146.in−addr.arpa 146.98.1.12 named.in−addr primary 0.0.127.in−addr.arpa named.local cache . named.cache ; The file points the named daemon to all sources of DNS information. One of these sources is the remote primary name server; others are local files in the specified directory varnamedxferd. Some of the files, such as named.hosts and named.in−addr, should be transferred from the primary name server, while the files named.local and named.cache are the primary source of information and have to be created locally a source host is not specified. The possible configuration directives configuration statements in the configuration file named.boot are summarized hereafter; a number of appropriate arguments are assigned to each of the implemented configuration directives. Directive Function Arguments directory Defines a directory for all subsequent file references A directory name primary Declares the server as primary for the specified zone A domain name and a file name secondary Declares the server as secondary for the specified zone A domain name, a primary server IP address, and a file name cache Points to the cache file root domain servers . the root domain name and a file name forwarders Lists servers to which queries are forwarded A forwarder name slave Forces the server to only use the forwarders 383 The primary name server is configured in a similar way, but the entries under secondary directives are replaced with primary directives. The configuration file for the corresponding primary server could be: cat etcnamed.boot ;−−−−−−−−−−−−−−−−−−etcnamed.boot−−−−−−−−−−−−−−−−−−−−−− ; directory varnamedzone ; ;type domain source host file ; primary myschoolrscps.edu named.hosts primary 98.146.in−addr.arpa named.in−addr primary 0.0.127.in−addr.arpa named.local cache . named.cache ; Even the names of the data files are the same; however, the referenced source directory is slightly renamed to reflect better the servers mission again this is an arbitrary move. However, the appropriate data files named.hosts and named.in−addr for this zone must be created from scratch — simply they are the primary and the only authoritative source of information for these zones. The same system can be the primary name server for certain zones, and the secondary name server for others in some ways every secondary server works like this — it is the primary server for the reverse local loop domain. Obviously only one primary name server can exist for a zone, but there can be a number of secondary servers. The secondary name servers for the same zone communicate with the corresponding primary name server, keeping their databases updated. All communication issues are defined by the primary server for a zone and written in the header of the appropriate data file. A data file is automatically transferred to all secondary servers at the beginning, and when it has been modified this is known as a zone−transfer. 16.3.1.2 Standard Resource Records The previously discussed named.boot file is the configuration file for the named daemon. All other referred data files named.hosts, named.in−addr, named.local, and named.cache store domain name database information. They all have the same basic format and use the same type of records; those records are known as standard resource records RR. BIND defines, in RFC 1033, the following RR types: 384 Start of authority SOA Marks the beginning of a zones data and defines parameters that affect the entire zone Name server NS Identifies a domains name server Address A Converts a host name to an IP address Pointer PTR Converts an IP address to a host name Mail exchange MX Identifies where to deliver e−mail for a given hosts domain name Canonical name CNAME Defines an alias host name Host information HINFO Describes a hosts hardware and OS Well−known services WKS Advertises hosts network services The format of a resource record is: name ttl IN type data where name The name of DNS object the RR references; it can be an individual host, or an entire domain. The name is relative to the current domain unless it ends with a dot; if a name is omitted, the RR applies to the last named object. ttl Time−to−live defines the length of time, in seconds, that the information in this RR should be kept in the cache. Usually it is omitted and the default minimal value set for the entire zone is applied. IN An Internet class of the RR type Identifies the RR type according to the previous table data The information specific to the RR type: SOA A list of appropriate parameters for the zone NS A name server domain name A An IP address PTR A host domain name CNAME An alias host name MX A mail exchange host name HINFO Abbreviated hardware and OS descriptions WKS A list of implemented network services, etc.

16.3.1.3 The Resource Record Files