Between questions and answers, DNS doubts are dying out

Q: What is "DNS"? What is its Chinese?

A: DNS, simply put, is the Domain Name System, translated into Chinese is the "domain name system."

Q: What is the purpose of DNS?

A: In a TCP /IP architecture of the network (eg Internet) environment, DNS is a very important and commonly used system. The main function is to convert the Domain Name, which is easy to remember, with the IP Address, which is not easy to remember. The network host that performs the DNS service above can be called a DNS Server. Basically, we usually think that DNS just converts the Domain Name to an IP Address and then uses the IP Address found to connect (commonly known as "forward resolution"). In fact, the function of converting IP Address to Domain Name is quite often used. When login to a Unix workstation, the workstation will do a reverse check to find out where you came from. (commonly known as " Reverse resolution").

Q: How does DNS work?

A: DNS is to use layers to operate. For example, the Domain Name of the Harbin Institute of Lilacs is bbs.hit.edu.cn. This Domain Name is of course not out of thin air and is assigned from .edu.cn. .edu.cn is also granted from .cn. Where did .cn come from? The answer is from the ".", the so-called "root domain". The root field is already the top level of the Domain Name. The "." layer is managed by InterNIC (Internet Network Information Center). The Domain Name of the world is like this, and it is granted layer by layer.

Q: When I check a Domain Name, how does DNS find out its IP?

A: For example, suppose today we check the Domain Name (for a dns query) is bbs.hit.edu.cn, DNS Server to be so treated: //article from computer hardware and software network applications Www.45it.com

(1) The computer you are using (may be a PC or a workstation) sends a question to the DNS Server set up by this computer. Ask: bbs.hit.edu. What is the IP of cn?

(2) that DNS will first see if it is in its cache, and if so, would throw the answers. If not, look up from the top. There must be a "." on the DNS Server to ask who to ask. Therefore, at this time, it goes to any DNS of the "." layer (currently "." has 13). Q: Who is the .cn to ask?
(3) "." Layer DNS will answer.cn to whom to check (and your DNS will cache this answer).

(4) Next, you use the .cn DNS DNS will ask this layer: .edu.cn ask who?

(5) .cn this layer will answer .edu.cn who want to check (and you can also use the DNS cache this answer up).

(6) until bbs.hit.edu.cn answer: bbs.hit.edu.cn of IP is 202.118.224.2 (and cache them).

After so many processes, I finally got this IP, and then I can make further connections. It's important to note that you will ask a question at each level, and write down the answer (cache), and you will forget it (see how long the layer is set to cache).

Q: How to set up DNS?

A: If you only want to use DNS, you can set that as long as the TCP /IP network properties. The method of setting is related to the operating system used. For example: Windows 9x in the "Control Panel" → "Network" → "TCP /IP" → "Properties", find the DNS part and then set. Unix is ​​set in the /etc/resolv.conf file (if you are setting up a DNS Server, it is not discussed here).

Q: Which DNS information is up to date?

A: If you know DNS is the use of hierarchy of operation, you should know that your nearest DNS, is the best.