There are several domain registars. This site provides info regarding domain registars www.networksolutions.com/.
If one is just looking for general information regarding domain names there is a large amount of information that can be found on the Wikipedia website. If one wishes to search domain names to find availability for a domain name, this can be done on the Go Daddy website.
There are many companies that offer domain registration, but if you are just looking for information, you should start here: http://en.wikipedia.org/wiki/Domain_name_registry
When looking to find information about broadcast domain then it may be worth visiting the Learning Network dot Cisco website as it offers information and services relating to broadcast domains.
There are many different ones online. Some are free and some you have to buy a domain. Weebly and Webs are good, free domain creators. It depends on what you are looking for. There are 1,000s to choose from.
You can find out this information easily at sites which offer this service by looking up the DNS records of a domain name. You can also find this service on the official home of domain names, Nominet.
Whois is a resource for discovering who owns a particular domain. One would just need to enter the name of the domain into the search box on the page and they will find the information they are looking for.
The practical domain is the domain by simply looking at the function. Whereas the mathematical domain is the domain based on the graph.
Domain
Probably the best place to find out a wide range of information on domain services would be the website GoDaddy. On the site one can get information on website building, hosting services and all the different web tools available.
The ORG domain name was originally created for non-profit organizations, but today is also used by schools, projects, and even for-profit companies. If you are looking to register a org domain name, then GoDaddy would be a good resource, as they will allow you to register such a domain.
Information technology is the application of telecommunication equipment and computers. Software applications are used for different areas that include customer support, sending, and receiving information. Computer hardware, software, and Internet telecom equipment are part of information technology.
There are many companies that sell domains. GoDaddy is a popular one, known for its television ads. If one is only looking for information about domain sales and not actually interested in buying a domain, online publications like 'DNJournal' have information about how much various domains have sold for.