What is the domain in networks?

In a workgroup:•All computers are peers; no computer has control over another computer.•Each computer has a set of user accounts. To log on to any computer in the workgroup, you must have an account on that computer.•There are typically no more than twenty computers.•A workgroup is not protected by a password.•All computers must be on the same local network or subnet.

  In a domain:•One or more computers are servers. Network administrators use servers to control the security and permissions for all computers on the domain. This makes it easy to make changes because the changes are automatically made to all computers. Domain users must provide a password or other credentials each time they access the domain.•If you have a user account on the domain, you can log on to any computer on the domain without needing an account on that computer.•You probably can make only limited changes to a computer's settings because network administrators often want to ensure consistency among computers.•There can be thousands of computers in a domain.•The computers can be on different local networks.

A group of computers and divices on a network that are administered as a unit with common rules and procedures. Within theinternet.

I think you are asking this question regarding to routing and switch because you selected CCNA, CCNP, Routing Protocol and cisco Specialization group.

According to that you might have listen to thing BROADCAST DOMAIN and Collision DOMAIN.

Broadcast domain : means the reachibility  of a broadcast packet you called one broadcast domain.

Collision Domain: where your collision of your packet occur

Domin comes in switching scenario which devides the network into different groups. An the members of that particular group can communicate between each other and the domain traffic is controlled by root bridge of that particula domain

A workgroup is a number of computers/devices/hosts that can share files and resources among themselves.But workgroup doesn't have central administration or control

So, domain is also intended to share files and resources but domain has central administration/control by a central server which is called domain controller.It enhanced security and performance of network as well as.Also became easier for domain administrators to deploy critical tasks because domain admin has priviledge whole over the domain.Usually, it is denoted by domain name like as: microsoft.com

**Remember that to create a  domain you don't need internet**

WIndows Domain is the  collection of  grouped computer which shared centre security data base. it is created by microsoft  to centralize the management of  the network resource. windows  domain is implemented by installing active directory which authenticate and authorize domain objects as such: computers shared folder & users.etc.Domain provides cenral managment system, entire domain network can be handled by domain administrator from a central location using GPO.

The DNS Domain Name System translates Internet domain and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites.

On the Internet, a domain is part of every network address, including web site addresses, email addresses, and addresses for other Internet protocols such as FTP, IRC, and SSH. All devices sharing a common part of an address, or URL, are said to be in the same domain.To obtain a domain, you must purchase it from a domain registrar.Internet domains are organized by level. Most people are familiar with the Top Level Domains (TLDs) of .com, .net,.org,etc. TLDs are the most general and basic part of the URL. There are actually many top level domains..net domain indicate organizations involved in networking technologies, such as Internet service providers and other infrastructure companies,.com web site addresses were for those publishers out to make some kind of profit through their Internet services,.org website website that related to an organization. Owning a domain name involves registering the name you want with an organization called ICANN through a domain name registrar like XnYnZ.com