Google Public DNS for faster Web

Google has recently announced its Google Public DNS services for web engines. Web pages are becoming more complex, including more resources from multiple origin domains and clients need to perform multiple DNS look ups to render a single page. Normally an internet user performs hundreds of DNS look ups each day, slowing down his/her browsing experience and as the web continues to grow greater loads are placed on the existing DNS infrastructure.

Google being the giant of search engines crawls the web on a daily basis and in the process resolves and caches DNS information and in this effort Google is leveraging its technology to experiment with new ways to address the challenges in performance nd security. The Google Public DNS service will achieve the following aims:

• Provide end users with an alternative to their current DNS service. Google Public DNS takes some new approaches that we believe offer more valid results, increased security, and, in most cases, better performance.
• Help reduce the load on ISPs’ DNS servers. By taking advantage of our global data-center and caching infrastructure, we can directly serve large numbers of user requests without having to query other DNS resolvers.
• Help make the web faster and more secure. We are launching this experimental service to test some new ways to approach DNS-related challenges. We hope to share what we learn with developers of DNS resolvers and the broader web community and get their feedback.

In this article I will take you through using the Google DNS service. The Google DNS service is available on the following IP addresses:

• 8.8.8.8
• 8.8.4.4

Very simple and easy to remember. You can use either numbers as your primary and secondary DNS servers. Changing the DNS settings will vary depending on your operating system.

A PDF guide to setting up your DNS servers from Google is available here

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

1. Go the Control Panel.
2. Click Network and Internet, then Network and Sharing Center, then Manage network connections.
3. 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.

4. Select the Networking tab. Under This connection uses the following items, click Internet Protocol Version 4 (TCP/IPv4), and then click Properties.
5. 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.
6. Click OK.
7. 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.
8. Replace those addresses with the IP addresses of the Google DNS servers: 8.8.8.8 and 8.8.4.4.
9. Restart the connection you selected in step 3.
10. Test that your setup is working correctly; see Testing your new settings below.
11. 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

1. From the Apple menu, click System Preferences, then click Network.
2. If the lock icon in the lower left-hand corner of the window is locked, click the icon to make changes, and when prompted to authenticate, enter your password.
3. 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 click Advanced.
4. Select the DNS tab.
5. 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.
6. Click Apply and OK.
7. Test that your setup is working correctly; see Testing your new settings below.
8. Repeat the procedure for additional network connections you want to change.

Linux

In most modern Linux distributions, DNS settings are configured through Network Manager.

Example: Changing DNS server settings on Ubuntu

1. In the System menu, click Preferences, then click Network Connections.
2. Select the connection for which you want to configure Google Public DNS. For example:
   • To change the settings for an Ethernet connection, select the Wired tab, then select your network interface in the list. It is usually called eth0.
   • To change the settings for a wireless connection, select the Wireless tab, then select the appropriate wireless network.
3. Click Edit, and in the window that appears, select the IPv4 Settings tab.
4. If the selected method is Automatic (DHCP), open the dropdown and select Automatic (DHCP) addresses only instead. If the method is set to something else, do not change it.
5. In the DNS servers field, enter the Google Public DNS IP addresses, separated by a space: 8.8.8.8  8.8.4.4
6. Click Apply to save the change. If you are prompted for a password or confirmation, type the password or provide confirmation.
7. Test that your setup is working correctly; see Testing your new settings below.
8. Repeat the procedure for additional network connections you want to change.

If your distribution doesn’t use Network Manager, your DNS settings are specified in /etc/resolv.conf.

Example: Changing DNS server settings on a Debian server

1. Edit /etc/resolv.conf:

   sudo vi /etc/resolv.conf

2. If any nameserver lines appear, write down the IP addresses for future reference.
3. Replace the nameserver lines with, or add, the following lines:

   nameserver 8.8.8.8
   nameserver 8.8.4.4

4. Save and exit.
5. Restart any Internet clients you are using.
6. Test that your setup is working correctly; see Testing your new settings below.

Additionally, if you are using DHCP client software that overwrites the settings in /etc/resolv.conf, you will need to set up the client accordingly by editing the client’s configuration file.

Example: Configuring DHCP client sofware on a Debian server

1. Back up /etc/resolv.conf:

   sudo cp /etc/resolv.conf /etc/resolv.conf.auto

2. Edit /etc/dhcp3/dhclient.conf:

   sudo vi /etc/dhcp3/dhclient.conf

3. If there is a line containing domain-name-servers, write down the IP addresses for future reference.
4. Replace that line with, or add, the following line:

   prepend domain-name-servers 8.8.8.8, 8.8.4.4;

5. Save and exit.
6. Restart any Internet clients you are using.
7. Test that your setup is working correctly; see Testing your new settings below.

Routers

Every router uses a different user interface for configuring DNS server settings; we provide only a generic procedure below. For more information, please consult your router documentation.

Note: Some ISPs hard-code their DNS servers into the equipment they provide; if you are using such a device, you will not be able to configure it to use Google Public DNS. Instead, you can configure each of the computers connected to the router, as described above.

To change your settings on a router:

1. In your browser, enter the IP address to access the router’s administration console.
2. When prompted, enter the password to access network settings.
3. Find the screen in which DNS server settings are specified.
4. If there are IP addresses specified in the fields for the primary and seconday DNS servers, write them down for future reference.
5. Replace those addresses with Google IP addresses: 8.8.8.8 and 8.8.4.4.
6. Save and exit.
7. Restart your browser.
8. Test that your setup is working correctly; see Testing your new settings below.

Mobile or other devices

DNS servers are typically specified under advanced wi-fi settings. However, as every mobile device uses a different user interface for configuring DNS server settings, we provide only a generic procedure below. For more information, please consult your mobile provider’s documentation.

To change your settings on a mobile device:

1. Go to the screen in which wi-fi settings are specified.
2. Find the screen in which DNS server settings are specified.
3. If there are IP addresses specified in the fields for the primary and seconday DNS servers, write them down for future reference.
4. Replace those addresses with Google IP addresses: 8.8.8.8 and 8.8.4.4.
5. Save and exit.
6. Test that your setup is working correctly; see Testing your new settings below.

Testing your new settings

To test that the Google DNS resolver is working:

1. From your browser, type in a hostname, such as http://www.google.com. If it resolves correctly, bookmark the page, and try accessing the page from the bookmark. If both of these tests work, everything is working correctly. If not, go to step 2.
2. From your browser, type in a fixed IP address. You can use http://74.125.53.100/(which points to the website http://www.google.com/) as the URL. If this works correctly, bookmark the page, and try accessing the page from the bookmark. If these tests work (but step 1 fails), then there is a problem with your DNS configuration; check the steps above to make sure you have configured everything correctly. If these tests do not work, go to step 3.
3. Roll back the DNS changes you made and run the tests again. If the tests still do not work, then there is a problem with your network settings; contact your ISP or network administrator for assistance.

Switching back to your old DNS settings

If you had not previously configured any customized DNS servers, to switch back to your old settings, in the window in which you specified the Google IP addresses, select the option to enable obtaining DNS server addresses automatically, and/or delete the Google IP addresses. This will revert your settings to using your ISP’s default servers.

If you need to manually specify any addresses, use the procedures above to specify the old IP addresses.

If necessary, restart your system.