Computer Network Review Guide

1. Answer: The Internet is a network of networks. These networks connect together in many ways to make what we know as the internet. The name internet comes from interconnected networks.

2. What is a Point of presence?

Answer：Point of Presence (PoP) is an access point to the internet; it is a site where a telecommunications company has their equipment. The equipment is usually, modems, leased lines and routers. An Internet Service Provider (ISP) usually has many PoPs in their area to make sure that their users have a local connection.

3. What’s a NAP?

Answer: NAP is Network Access Point; it is the connection between an ISP and the internet.

4. What’s an internet backbone?

Answer: A backbone is when a company uses equipment to get a fast connection to the internet. This usually means laying down huge cables that have a lot of bandwidth.

(Next, Figure 1 will you give a general idea of the concepts we mention here!)

5. What is a router?

Answer: Router is a device that forwards data packets between computer networks

6. What’s a DNS?

Answer: Domain Name System (DNS), which maps text names to IP addresses automatically. DNS servers accept requests from programs and other name servers to convert domain names into IP addresses.

7. Answer: IP address works on the network layer, It is the unique identifier(标识) of each host on the internet.

8. Answer: Applications use the Ping class to detect whether a remote computer is reachable. A successful Ping indicates only that the remote host can be reached on the network.

9. What’s IPCONFIG used for?

Answer: IPCONFIG is a Console Command which can used to display the network settings currently assigned to any or all network adapters in the machine. This command can be utilized to verify a network connection as well as to verify your network settings. It can also be used to release, or refresh the IP Address. This is useful for dynamic IP addresses.

10. Answer: The Trace Route utility checks how many ―hops‖ it takes for your computer to contact another. A ―hop‖ is how many compu ters it goes through in the network to get to the destination. It will give you a return massage when it goes through a host in the network.

11. What’s ICMP?

Answer: The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet Protocol Suite. It is mostly used by operating systems to send messages (e.g. that a requested service is not available, or a host cannot be reached). Without ICMP, we would never know what happened if an error encountered by our packets on the network, or Internet. To program a ping, or trace route program, you should know how ICMP works.

12. What is the difference between synchronous and asynchronous?

Answer: Synchronous Is when one task is done in sequence.

Each task must wait until the one before is finished.

Asynchronous：Each task doesn’t have to wait for the one before to be finished.Each task can start when needed.It is better for updating the user.