Security In Mind

Domain Name System (DNS)

Domain Name System (DNS)

When the Internet was small, the association of domain names with IP addresses could fit into single text file . The networked computers were few therefore communication was simple.

The hostname of the computer on a network were managed through the use of a single host located on a centrally administered server.

Each site which needed to resolve the hostname on a network downloaded the host file from a central server and this became a challenge when the number of host and networks grew and two major bottlenecks appeared:

→ The host file became bigger
→ The traffic load on the central server increased

Therefore the need for a new system was required

→ One that was scalable
→ Provided decentralized administration
→ Also one that could handle the name resolution of the domain names to IP addresses since it was a growing need.

The Domain Name System also became both distributed and dynamic, unlike our previous hosts file. It did not rely upon one file or one server, but instead upon many files across many servers across the globe.

These servers were organized in a hierarchical manner. Due to this distributed nature, the DNS system became resistant to outages of one or many of these servers.

The host name resided on a database that was distributed among multiple servers decreasing the load of any one server and providing the ability to administer this naming system on a domain or zone partion basis.

To read more about Host files

The Domain Name System

Essentially is a service that provides a phone directory for the Internet. Its the Internet Directory Service.

The DNS is a distributed database implemented in a hierarchy of name servers and an application-layer protocol that allows hosts and name servers to communicate in order to provide the translation service.

It was designed to translate a domain name – something people are rather good at remembering – into an IP address,the language of Internet Routing. Think of DNS as simply a translation of a domain name to their respective IP addresses. So, when you enter a domain such as into your browser, it is translated into a computer-friendly IP address that the Internet can understand and route.

IP addresses are unique identifiers in a machine-readable system.Hostnames assign names for computers, webservers, or interfaces to the respective IP addresses so that the hosts can be addressed without knowledge of IP addresses. The domain name system resolves IP addresses (and thus also hostnames) in such a way that human users can find these computers, network nodes or interfaces.

Every host on the Internet has a unique IP address and a domain name.The network namespace is one the component / elements of the DNS which is a set of all hostnames that changes dynamically with time due to addition/deletion of hosts, regrouping of local work groups, reconfiguration of sub-parts of the network, maintenance of systems and networks, and so on. So, new domain names, new IP addresses, and new domain-to-IP associations can be introduced in the namespace at any time without a central control.

A hostname is a unique name for a computer or network node in a network. Hostnames are specific names that refer to a host. They can describe both physical addresses and network nodes, which have multiple domains under one host. The same gets applies to the world wide web, where hostnames are resolved into IP addresses via the domain name system, so that each network user gets a one-to-one description, regardless of whether it is a computer, a network node at the Internet provider or a web server.

Network protocol – http://

Hostname –

Domain –

If the hostname is complete, it is referred to as a Fully-Qualified Hostname (FQHN) or Fully-Qaulified Domain name (FQDN).

The domain name consists of the domain and the Top-Level Domain (.org) and should be distinguished from the hostname even if both versions direct to the same address.

Some of general characteristics of hostnames include:

> Hostnames are mnemonic and are therefore appreciated by humans.
> Hostnames provide little information about the location within the Internet of the host.
> Hostname such as, which ends with the country code .ke, tells us that the host is in Kenya, but doesn’t say much more.
> Furthermore, because hostnames can consist of variable-length alpha-numeric characters, they would be difficult to process by routers.

Hostnames can represent physical or virtual addresses. Some examples:
> The domain name my gets assigned the hostname, so that the server is reachable.
> The hostname contains the domain name
> The hostname denotes a network node with an Internet service provider, which has a completely different domain name.
> The hostname mail. can be selected as the name for an internal e-mail server in a private network. The same applies to FTP services and virtual networks.

Hostnames are often confused with domains. However, different hosts can be grouped under one domain, similar to subdomains. Hostnames can also coincide with domain names, but don’t have to. In the network architecture, hostnames are still often used to distinguish clients from each other. For example, when creating content for domains, because content is simulated to be on the web, even though it is only stored locally.


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