DNS full Q &

Q: What is "DNS "? Why is it Chinese?
A: DNS, simply put, is the Domain Name System. If it is translated into Chinese, it is the "Domain Name System ".

Q: What is the purpose of DNS?
A: In a TCP/IP network (such as the Internet) Environment, DNS is a very important and common system. The main function is to convert Domain names that are easy to remember and IP addresses that are hard to remember. The network host that runs the DNS service above can be called the DNS Server. Basically, we usually think that DNS only converts Domain Name to IP Address, and then uses the IP Address to connect (commonly known as "forward resolution "). In fact, the function of converting an IP Address to a Domain Name is also quite common. When login is sent to a Unix workstation, the workstation will perform reverse lookup, find out where you are connecting (commonly known as "reverse resolution ").

Q: How does DNS work?
A: DNS operates in layers. For example, the Domain Name of the Harbin Institute of Technology is bbs.hit.edu.cn. This Domain Name is not from the air, but is allocated from .edu.cn .. Edu.cn is also granted from. cn (delegation .. Where does cn come from? The answer is from ".", that is, the so-called "root domain. The root Domain is already the top layer of Domain Name. The "." layer is managed by InterNIC (Internet Network Information Center. Domain names all over the world are granted at one layer.

Q: When I check a Domain Name, how does DNS find its IP address?
A: for example, if the Domain Name we checked today (as a dns query) is bbs.hit.edu.cn, the DNS Server will handle this:
(1) Your Computer (either a PC or a workstation) sends a question to the DNS Server set for this computer. Question: What is the IP address of bbs.hit.edu.cn?
(2) This DNS will first check whether it is in its cache. If so, the answer will be lost. If not, check the top header. On the DNS Server, you must set "." To ask who to ask. So at this time, it will go to any DNS on the "." layer (currently "." has 13 servers) and ask: Who should I ask?
(3) The DNS at the "." layer will answer to who the. cn Domain is going to query (and the DNS you are using will cache the answer ).
(4) Next, the DNS you use will ask the DNS at the. cn layer: .edu.cn who will ask?
(5) On this layer of. cn, the answer will be .edu.cn to whom you want to query (and the DNS you use also caches the answer ).
(6) until bbs.hit.edu.cn replied: the IP address of bbs.hit.edu.cn is 202.118.224.2 (cache again ).

After so many processes, I finally got this IP address, and then I can make further connections. It should be noted that a question is asked at each layer, and the answer is recorded (cache starts), and it will be forgotten (it depends on how long it takes to cache the layer ).

Q: How do I configure DNS?
A: If you only want to use DNS, you only need to set it in the Network Properties of TCP/IP. The setting method is related to the operating system used. For example, for Windows 9x, find the DNS part in "Control Panel"> "network"> "TCP/IP"> "properties" and set it. Unix is set in the/etc/resolv. conf file (if you want to set up a DNS Server, it is not discussed here ).

Q: Which DNS is the latest?
A: If you know that DNS runs in a hierarchical architecture, you should know that the DNS closest to you is the best.

Article entry: dnbm responsibility Editor: dnbm