Google发布免费DNS解析服务

Google 免费的DNS解析服务。是Web的重要组成部分，它就如同是互联网的“电话簿”。每次访问一个网站，计算机都须执行一次DNS查询。复杂的网页在载入之前需执行多次DNS查询，其结果是普通网民每天必须执行数百次DNS查询，这会降低用户的浏览体验。Google推出Public DNS便是试图改进浏览体验，让互联网变得更快(在TTL记录过期之前执行prefetching，更新缓存)，更安全（支持新的DNS安全扩展）。Google Public DNS托管在Google分布在全世界的数据中心，它使用选播路由算法（Anycast Routing）把用户的DNS解析请求发送到地理位置最近的数据中心。Google Public DNS遵循DNS标准，向用户的计算机提供正确的响应，不会有任何屏蔽、过滤，或重新定向等妨碍用户浏览体验的行为。Google Public DNS的IP地址为：8.8.8.8以及8.8.4.4。
修改TCP/IP的DNS服务器地址：Microsoft Windows
DNS settings are specified in the TCP/IP Properties window for the selected network connection.
Example: Changing DNS server settings on Microsoft Windows Vista
Go the Control Panel.
Click Network and Internet, then Network and Sharing Center, then Manage network connections.
Select the connection for which you want to configure Google Public DNS. For example:To change the settings for an Ethernet connection, right-click Local Area Connection, and click Properties.
To change the settings for a wireless connection, right-click Wireless Network Connection, and click Properties.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Select the Networking tab. Under This connection uses the following items, clickInternet Protocol Version 4 (TCP/IPv4), and then click Properties.
Click Advanced and select the DNS tab. If there are any DNS server IP addresses listed there, write them down for future reference, and remove them from this window.
Click OK.
Select Use the following DNS server addresses. If there are any IP addresses listed in the Preferred DNS server or Alternate DNS server, write them down for future reference.
Replace those addresses with the IP addresses of the Google DNS servers: 8.8.8.8 and 8.8.4.4.
Restart the connection you selected in step 3.
Test that your setup is working correctly; see  below.
Repeat the procedure for additional network connections you want to change.
Mac OS X
DNS settings are specified in the Network window.
Example: Changing DNS server settings on Mac OS 10.5
From the Apple menu, click System Preferences, then click Network. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Select the connection for which you want to configure Google Public DNS. For example:To change the settings for an Ethernet connection, select Built-In Ethernet, and click Advanced.
To change the settings for a wireless connection, select Airport, and clickAdvanced.
Select the DNS tab.
Click + to replace any listed addresses with, or add, the Google IP addresses at the top of the list: 8.8.8.8 and 8.8.4.4.
Click Apply and OK.
Test that your setup is working correctly; see  below.
Repeat the procedure for additional network connections you want to change.
Linux
DNS settings are specified in /etc/resolv.conf in most distributions.
Example: Changing DNS server settings on Ubuntu
Edit /etc/resolv.conf:sudo vi /etc/resolv.conf
If any nameserver lines appear, write down the IP addresses for future reference.
Replace the nameserver lines with, or add, the following lines:nameserver 8.8.8.8
nameserver 8.8.4.4
Save and exit.
Restart any Internet clients you are using.
Test that your setup is working correctly; see  below.
PS:4.3.2.1 也是 Google 的 DNS, 不过没公开公布, L3的DNS: 4.2.2.1-4