Container is a term that describes an isolated IT hosting environment which runs its own Operating System (OS) alone, which might or might not be a different type of OS than the one of the underlying physical server (infrastructure). Unlike the other Virtual Servers (Virtual Machines), the so-called Containers are created through a virtualization technique called OS Virtualization. It is a software assisted virtualization, which allows any computer hardware to run multiple instances with separate OS concurrently.

The instances (VEs), also containers, work like a separate, real computers. Any software application running on a standard  Operating System can use all resources – CPU power, memory and other computing resources as well as files and folders – of a Container based computer.

Containers crated thought an OS Operating virtualization does not feature the same level of flexibility as the Virtual Machines created with full virtualization, for example. A Container cannot use an OS different from the one that runs on the underlying physical server, or a different guest kernel. If the underlying host runs any Linux distribution, the Containers that run on top of it cannot run Windows.

The Domain Name System is an Internet naming system that makes it possible to assign domain names to groups of Internet resources and users, independent of each entity’s physical location. Domain names are easier to remember than IP addresses such as 207.75.188.166 (IPv4) or 2001:db6:1f70::999:de8:7648:6e8 (IPv6). Internet users use domain names to recite meaningful Uniform Resource Locators (URLs) and e-mail addresses.

The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating name servers for each domain. Name servers are responsible for their particular domains. The are DNS distributed and fault tolerant. This makes possible for the WWW to avoid keeping everything in a single central register which has to be continually consulted and updated.

Domain Name System also stores information about the list of mail servers that accept email for web addresses. Domain Name System is a very important component of the Internet as we know it because it provides a distributed keyword-based redirection service.