DNS (Domain Name System) was developed to provide a more user-friendly way than IP addresses to identify network locations.
DNS(域名系统)是为了提供一种比IP地址更用户友好的方式来识别网络位置而开发的。
>> Do me a favor.
请帮我个忙。
Take out your phone.
拿出你的手机。
How many phone numbers are stored in your phone?
你的手机里有多少个电话号码?
Okay, out of all these numbers, how many can you dial on your ownwithout accessing the Contacts or Favorites?
好吧，在所有这些号码中，有多少你可以自己拨打而不访问联系人或收藏夹?
Don't ask Siri or Cortana, either.
也不要问Siri或Cortana。
I don't know how we did it before Favorites and Contacts lists in today's phones,but I fully rely on my Favorites, Contacts list, and Siri.
我不知道在今天的手机上有收藏夹和联系人列表之前我们是怎么做到的，但我完全依赖我的收藏夹、联系人列表和Siri。
Imagine if we had to memorize IP addresses of websites and network resources.
That would be kind of tough.
想象一下，如果我们必须记住网站和网络资源的IP地址。
这有点困难。
But let's say we did in fact memorize the IP addresses of our favorite websites and then,for one reason or another, some IP addresses changed.
但是假设我们确实记住了我们最喜欢的网站的IP地址，然后，由于这样或那样的原因，一些IP地址改变了。
Well, originally, you either had to access resources by IP addressesor use a text file called Hosts, found on all operating systems.
最初，您必须通过IP地址访问资源，或者使用在所有操作系统上都可以找到的名为Hosts的文本文件。
Into the Hosts file you typed an IP address and its FQDN --fully qualified domain name or web address.
在主机文件中键入IP地址及其FQDN——完全限定的域名或web地址。
Today's operating systems still have the Hosts file,but it's not used anymore for that purpose.
今天的操作系统仍然有Hosts文件，但不再用于此目的。
We don't collect web addresses and IP addresses and type the pair into the Host file.
我们不收集web地址和IP地址并将它们输入主机文件。
It's not scalable.
这不是可伸缩。
And IP addresses of websites change.
和网站的IP地址变化。
Wouldn't it be better to type www.rit.edu into a browser, instead of memorizingthat server's IP address is 12921140?
在浏览器中输入www.rit.edu不是比记住服务器的IP地址12921140更好吗?
If Google stored an indexed IP addresses instead of FQDNs of websites,and a website's IP address changed,Google results would be incorrect, inconsistent, and unpredictable.
如果谷歌存储的是编入索引的IP地址，而不是网站的FQDNs，并且网站的IP地址发生了变化，谷歌的结果将是不正确的、不一致的和不可预测的。
Google also realizes that storing IP addresses is a flawed idea.
谷歌也意识到存储IP地址是一个有缺陷的想法。
When a website's IP address changes due to reorganization of the networking, new ISP,a company merger, or anything like that, Google doesn't need to be notified.
当一个网站的IP地址由于网络重组、新的ISP、公司合并或类似的事情而改变时，谷歌不需要被通知。
The same thing applies to a phone's Contacts list.
同样的道理也适用于手机的通讯录。
When one of my friends sends me a new phone number, I will replace the old onewith the new one in my Contacts list.
当我的一个朋友给我发了一个新的电话号码，我会在我的联系人列表中用新的号码代替旧的号码。
That's like a change to a server's IP address being made at the company.
这就像公司正在对服务器的IP地址进行更改。
The next time I ask Siri for Bob's cell phone,I will be asking the same way I did before Bob changed his phone number.
下次我向Siri要Bob的手机时，我问的方式和Bob改电话号码前一样。
Siri will dial the new number because Siri will be referencing the same entry --the name of my friend, who now has a different phone number associated with the Contact name.
Siri会拨这个新号码，因为Siri会引用同一个条目——我朋友的名字，他现在有了一个与联系人名字相关联的不同电话号码。
Think of an IP address for a server that changes,while the name of that machine stays the same.
考虑一个服务器的IP地址发生了变化，而该服务器的名称保持不变。
转载于:https://www.cnblogs.com/sec875/articles/10380968.html
