“Any domain name in the subtree is consider a part of the domain. In the similar fashion there can be many domains in the “sjsu” domain. The domain name of a domain is the same as the domain name of the node at the very top of the domain.” Consider the figure belowĪs you can see in the figure above that the “sjsu” domain is a part of the edu domain. “A domain is simply a subtree of the domain name space. you can not have multiple directories named “Program Files” in one single directory, but if you wish you can have a directory name “Program Files” in your root directory of your C drive, and in the “C:\Windows” directory (or in any number of distinct directory locations). This guarantees that each domain name in the DNS tree corresponds to unique domain name in the entire DNS structure.Į.g. No two nodes can have the same name if and only if they have the same parent. Domain name is read from the node to the root with a dot placed separating the names in the path. The full domain name of any node in the tree is the sequence of each node in that path from the node to the root. Each node in a tree represents its part in a domain name which can contain a maximum of 63 characters long. There can be a maximum of 127 levels in a tree however, you will never find any domain name that long. Each node in the tree is associated with a resource record which holds the information associated with it, and can have any number of branches. It is a tree-like structure in which the root is known as the Root DNS sever. The structure of DNS is similar to the structure of Unix file system. The decentralized administration is achieved through delegation.įig. The DNS is a distributed system, implemented in a hierarchy of many name servers. Problems that arise when we try to centralize DNS.Īs centralized DNS does not scale because of the reasons mentioned above, a need arose to implement DNS in a distributed manner. Once the BIND feature of DNS resolves the domain to one of the servers, subsequent requests from the same client are sent to the same server.” Why not centralize DNS? This redirects the request to one of the several servers in a server group. “When the request comes to the DNS server to resolve the domain name, it gives out one of the several canonical names in a rotated order. can be remembered easily but if the original mail server address, say, were to be used it would be difficult to rememberĪ set of IP address is provided to one canonical name which prevents the load to be present only on one server. It is highly desirable that an email address should contain simple letters, or should be something that can be easy to remember. It is used because a hostname may have a complicated name instead of that a simple term may be used. Host aliasing is referred to another name given to the same machine on the network. The backward facility (translating IP address to domain name) is known as Reverse DNS. The primary purpose of DNS is to provide translation of host name to IP address and vice versa. Every time when a host needs to convert a domain name to the IP address, a DNS query is called. (More details of IP address will be covered in further sections.)Īnswer. DNS provides mapping of IP address and Domain name. Therefore a name has been assigned to almost every IP address which makes it easier for humans to remember. To remember IP addresses of more than one host becomes cumbersome. Remembering IP addresses is difficult, as it contains all numbers. We need to know the IP address of that machine. Say if we need some information that is on other part of the world. In the similar fashion, every computer or host and router in the world has a unique identifying 32-bit ‘IP’ address. There are many identifiers to be a unique person in the world, such as SSN, name, and Passport number along with the county who issued it, etc. To begin with let’s start with a real world example. The very first question arise: ‘what is the need of this application?’. Out of those one is DNS, which stands for Domain Name System. The application layer consists of various applications. 17 Insert Resource Record in DNS Databaseĭomain Name System (DNS) Ī domain name identifies the area or domain that an Internet resource resides in.
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