How Domain Name Servers Work

If you've ever used the Internet, it's a good bet that you've used the Domain Name System, or DNS, even without realizing it. DNS is a protocol within the set of standards for how computers exchange data on the Internet and on many private networks, known as the TCP/IP protocol suite. Its basic job is to turn a user-friendly domain name like "howstuffworks.com" into an Internet Protocol (IP) addresslike 70.42.251.42 that computers use to identify each other on the network. It's like your computer's GPS for the Internet.

Computers and other network devices on the Internet use an IP address to route your request to the site you're trying to reach. This is similar to dialing a phone number to connect to the person you're trying to call. Thanks to DNS, though, you don't have to keep your own address book of IP addresses. Instead, you just connect through a domain name server, also called a DNS server or name server, which manages a massive database that maps domain names to IP addresses.

Whether you're accessing a Web site or sending e-mail, your computer uses a DNS server to look up the domain name you're trying to access. The proper term for this process is DNS name resolution, and you would say that the DNS server resolves the domain name to the IP address. For example, when you enter "https://www.howstuffworks.com" in your browser, part of the network connection includes resolving the domain name "howstuffworks.com" into an IP address, like 70.42.251.42, for HowStuffWorks' Web servers.

You can always bypass a DNS lookup by entering 70.42.251.42 directly in your browser (give it a try). However, you're probably more likely to remember "howstuffworks.com" when you want to return later. In addition, a Web site's IP address can change over time, and some sites associate multiple IP addresses with a single domain name.

Without DNS servers, the Internet would shut down very quickly. But how does your computer know what DNS server to use? Typically, when you connect to your home network, Internet service provider (ISP) or WiFi network, the modem or router that assigns your computer's network address also sends some important network configuration information to your computer or mobile device. That configuration includes one or more DNS servers that the device should use when translating DNS names to IP address.

So far, you've read about some important DNS basics. The rest of this article dives deeper into domain name servers and name resolution. It even includes an introduction to managing your own DNS server. Let's start by looking at how IP addresses are structured and how that's important to the name resolution process.
DNS Servers and IP Addresses

PREV NEXT

You just learned that the primary job of a domain name server, or DNS server, is to resolve (translate) a domain name into an IP address. That sounds like a simple task, and it would be, except for the following points:

  • There are billions of IP addresses currently in use, and most machines have a human-readable name as well.
  • DNS servers (cumulatively) are processing billions of requests across the Internet at any given time.
  • Millions of people are adding and changing domain names and IP addresses each day.

With so much to handle, DNS servers rely on network efficiency and Internet protocols. Part of the IP's effectiveness is that each machine on a network has a unique IP address in both the IPV4 and IPV6 standards managed by the Internet Assigned Numbers Authority (IANA). Here are some ways to recognize an IP address:

  • An IP address in the IPV4 standard has four numbers separated by three decimals, as in: 70.74.251.42
  • An IP address in the IPV6 standard has eight hexadecimal numbers (base-16) separated by colons, as in 2001:0cb8:85a3:0000:0000:8a2e:0370:7334. Because IPV6 is still a very new standard, we'll concentrate on the more common IPV4 for this article.
  • Each number in an IPV4 number is called an "octet" because it's a base-10 equivalent of an 8-digit base-2 (binary) number used in routing network traffic. For example, the octet written as 42 stands for 00101010. Each digit in the binary number is the placeholder for a certain power of two from 2 to 27, reading from right to left. That means that in 00101010, you have one each of 21, 23and 25. So, to get the base-10 equivalent, just add 21 + 23 + 25 = 2 + 8 + 32 = 42. For more about how IP addresses are constructed, see our article "What is an IP address?"
  • There are only 256 possibilities for the value of each octect: the numbers 0 through 255.
  • Certain addresses and ranges are designated by the IANA as reserved IP addresses, which means they have a specific job in IP. For example, the IP address 127.0.0.1 is reserved to identify the computer you're currently using. So, talking to 127.0.0.1 is just talking to yourself!

Where does your computer's IP address come from? If we're talking about your desktop or laptop computer, it probably comes from a Dynamic Host Configuration Protocol (DHCP) server on your network. The job of a DHCP server is to make sure your computer has the IP address and other network configuration it needs whenever you're online. Because this is "dynamic," the IP address for your computer will probably change from time to time, such as when you shut down your computer for a few days. As the user, you'll probably never notice all this taking place. See the sidebar on this page for hints on where to find the IP address assigned to your computer or mobile device.

Web servers and other computers that need a consistent point of contact use static IP addresses. This means that the same IP address is always assigned to that system's network interface when it's online. To make sure that interface always gets the same IP address, IP associates the address with the Media Access Control (MAC) address for that network interface. Every network interface, both wired and wireless, has a unique MAC address embedded in it by the manufacturer.

For more information on IP addresses, see the IANA, operated by the Internet Corporation for Assigned Names and Numbers (ICANN). Now, though, let's look at the other side of the DNS equation: domain names.

FINDING YOUR IP ADDRESS

The following are tips on how to find your computer's IP address. Note that the address will change periodically unless you've chosen to use a static IP (rare for end-users):

  • Windows -- Though you can click through the user interface to find your network interface settings, one quick way to find your IP address is to open the Command Prompt application from Accessories and enter this command: ipconfig
  • Mac -- Open your System Preferences, click Network, be sure your current network connection (with the green dot beside it) is selected, click Advanced, and click the TCP/IP tab.
  • Linux or UNIX -- If don't already have a command prompt, open a terminal application, such as XTERM or iTerm. At the command prompt, enter this command: ifconfig
  • Smartphones using WiFi -- Look at your phone's network settings. This will vary depending on the phone the version of its operating system.

Note that if you're on a home or small local network, your address will probably be in the form 192.168.x.x, 172.16.x.x or 10.x.x.x (where x is a number between 0 and 255). These are reserved addresses used on each local network, and a router on that network then connects you to the Internet.

最后编辑于
©著作权归作者所有,转载或内容合作请联系作者
  • 序言:七十年代末,一起剥皮案震惊了整个滨河市,随后出现的几起案子,更是在滨河造成了极大的恐慌,老刑警刘岩,带你破解...
    沈念sama阅读 217,406评论 6 503
  • 序言:滨河连续发生了三起死亡事件,死亡现场离奇诡异,居然都是意外死亡,警方通过查阅死者的电脑和手机,发现死者居然都...
    沈念sama阅读 92,732评论 3 393
  • 文/潘晓璐 我一进店门,熙熙楼的掌柜王于贵愁眉苦脸地迎上来,“玉大人,你说我怎么就摊上这事。” “怎么了?”我有些...
    开封第一讲书人阅读 163,711评论 0 353
  • 文/不坏的土叔 我叫张陵,是天一观的道长。 经常有香客问我,道长,这世上最难降的妖魔是什么? 我笑而不...
    开封第一讲书人阅读 58,380评论 1 293
  • 正文 为了忘掉前任,我火速办了婚礼,结果婚礼上,老公的妹妹穿的比我还像新娘。我一直安慰自己,他们只是感情好,可当我...
    茶点故事阅读 67,432评论 6 392
  • 文/花漫 我一把揭开白布。 她就那样静静地躺着,像睡着了一般。 火红的嫁衣衬着肌肤如雪。 梳的纹丝不乱的头发上,一...
    开封第一讲书人阅读 51,301评论 1 301
  • 那天,我揣着相机与录音,去河边找鬼。 笑死,一个胖子当着我的面吹牛,可吹牛的内容都是我干的。 我是一名探鬼主播,决...
    沈念sama阅读 40,145评论 3 418
  • 文/苍兰香墨 我猛地睁开眼,长吁一口气:“原来是场噩梦啊……” “哼!你这毒妇竟也来了?” 一声冷哼从身侧响起,我...
    开封第一讲书人阅读 39,008评论 0 276
  • 序言:老挝万荣一对情侣失踪,失踪者是张志新(化名)和其女友刘颖,没想到半个月后,有当地人在树林里发现了一具尸体,经...
    沈念sama阅读 45,443评论 1 314
  • 正文 独居荒郊野岭守林人离奇死亡,尸身上长有42处带血的脓包…… 初始之章·张勋 以下内容为张勋视角 年9月15日...
    茶点故事阅读 37,649评论 3 334
  • 正文 我和宋清朗相恋三年,在试婚纱的时候发现自己被绿了。 大学时的朋友给我发了我未婚夫和他白月光在一起吃饭的照片。...
    茶点故事阅读 39,795评论 1 347
  • 序言:一个原本活蹦乱跳的男人离奇死亡,死状恐怖,灵堂内的尸体忽然破棺而出,到底是诈尸还是另有隐情,我是刑警宁泽,带...
    沈念sama阅读 35,501评论 5 345
  • 正文 年R本政府宣布,位于F岛的核电站,受9级特大地震影响,放射性物质发生泄漏。R本人自食恶果不足惜,却给世界环境...
    茶点故事阅读 41,119评论 3 328
  • 文/蒙蒙 一、第九天 我趴在偏房一处隐蔽的房顶上张望。 院中可真热闹,春花似锦、人声如沸。这庄子的主人今日做“春日...
    开封第一讲书人阅读 31,731评论 0 22
  • 文/苍兰香墨 我抬头看了看天上的太阳。三九已至,却和暖如春,着一层夹袄步出监牢的瞬间,已是汗流浃背。 一阵脚步声响...
    开封第一讲书人阅读 32,865评论 1 269
  • 我被黑心中介骗来泰国打工, 没想到刚下飞机就差点儿被人妖公主榨干…… 1. 我叫王不留,地道东北人。 一个月前我还...
    沈念sama阅读 47,899评论 2 370
  • 正文 我出身青楼,却偏偏与公主长得像,于是被迫代替她去往敌国和亲。 传闻我的和亲对象是个残疾皇子,可洞房花烛夜当晚...
    茶点故事阅读 44,724评论 2 354

推荐阅读更多精彩内容

  • NAME dnsmasq - A lightweight DHCP and caching DNS server....
    ximitc阅读 2,852评论 0 0
  • Introduction An important part of managing server configu...
    㗊𨰻木㵘燚㙓㗊阅读 563评论 0 0
  • TABLE OF CONTENTS Introduction 7 Overview of FortiCloud 7...
    Bouw阅读 2,412评论 0 0
  • 江山易打不易守,每个朝代迭替,激进进取的时候似乎顶天立地,心怀百姓与天下,末期大多昏聩奢靡,一叶障目,就怕丢...
    心有所薯阅读 219评论 1 9
  • 夜,太阳收了光, 人神开始绽放。 迷路的伊卡洛斯, 找着冰冷的太阳。 流散的灯光, 倒映在天上。 走到哪里都是太阳...
    H3190阅读 206评论 0 1