18. What do all networks rely on? What does nap stand for? What is a trunk line comprised of?

There is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points or NAPs. All networks rely on NAPs, backbones and routers to talk to each other. Backbones are typically fiber optic trunk lines. The trunk line has multiple fiber optic cables combined together to increase the capacity. Today there are many companies that operate their own high-capacity backbones, and all of them interconnect at various NAPs around the world.

19. What facilities can the Internet provide?

The Internet provides various facilities, including email, instant messaging, social networking and video conferencing. These technologies allow people to communicate instantly from any part of the world at a relatively cheaper cost regardless of their geographical locations.

20. What is email? How does it work? What does an email address consist of?

E-mail is an electronic message that may contain text, files, images, or other attachments sent through a network to a specified individual or group of individuals. The mail you send is stored on the mail server in a simulated mailbox until the recipient downloads it.

There are two ways to get email over the Internet. You can use a mail program, called email client installed on your computer. The other way is to use web-based email from any browser. Email address has three parts: username, the @ sign (which means “at”) and the domain name that is the mail server where the account is located. The final part of it adds information about it, e.g. .com = company, .fr = France.

Email contains two main parts: the header (including the recipient’s / sender’s name and address and the subject of the message) and the body (the message itself).

21. What is a server and what is a client in the Internet system? How does a server make its service available?

Internet servers make the Internet possible. All of the machines on the Internet are either servers or clients. The machines that provide services to other machines are servers. And the machines that are used to connect to those services are clients. There are Web servers, e-mail servers, FTP (File Transfer Protocol) servers and so on serving the needs of Internet users all over the world. Any server machine makes its services available using numbered ports – one for each service that is available on the server.

22. What is dns? What function does dns perform?

When you want to send a message or retrieve information from another computer, your request goes out over the network, hitting domain name servers (DNS) along the way to find the target server. The DNS points the request in the right direction. Once the target server receives the request, it will send a response back to your computer. DNS is a system of matching names with numbers.

23. What path does your request follow when you want to send a message? What is a domain name?

When you want to send a message or retrieve information from another computer, your request goes out over the network, hitting domain name servers (DNS) along the way to find the target server. The DNS points the request in the right direction. Once the target server receives the request, it will send a response back to your computer. DNS is a system of matching names with numbers.