The Linux bind service detailed

1 Principles of DNS

Introduction to 1.1 DNS

DNS (domain Name System) domain name systems, in the TCP/IP network has a very important position, can provide domain names and IP address resolution services.

1.2 Domain name space

DNS is a distributed database, command system using a level of logical structure, like an inverted tree, the logical tree structure becomes domain name space, because DNS division domain name space, so the agencies can use their own domain name space to create DNS information

Note: In the DNS domain name space, the maximum depth of a tree must not exceed 127 levels, and each node in the tree can store up to 63 characters in length.

(1) Domain and domain name

Each node of the DNS tree represents a domain, through these nodes, the whole domain name space is divided into a hierarchy, the name of each domain of domain name, through the domain name, the domain name is usually identified by a full official domain name (FQDN), the FQDN can accurately represent its location relative to the root of the DNS domain, That is, the full representation of nodes to the DNS domain root, from node to tree root in the direction of writing, and the use of each node "." delimited, for DNS domain Itchenyi, its fully fledged domain name FQDN is itchenyi.com.

A DNS domain can include hosts and other domains (subdomains), each of which has the authority of a part of the namespace, is responsible for the management and division of that part of the namespace, and uses it to name DNS domains and computers, for example, Itchenyi as a subdomain of COM domains, Its representation is itchenyi.com, and www is the Web in Itchenyi domain, which can be represented with www.itchenyi.com!

Note: Typically, the FQDN has strict naming restrictions that are not longer than 256 bytes, allowing only characters a-z,0-9,a-z and minus signs (-). The point number (.) is only allowed to be used between domain name flags, such as "itchenyi.com" or the end of the FQDN. Domain names are not case-sensitive.