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Using Google Public DNS
Posted by John Roberts, Last modified by Chris Johnson on 12 October 2015 12:48 PM
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Using Google Public DNS
Configuring your network settings to use Google Public DNSWhen you use Google Public DNS, you are changing your DNS "switchboard" operator from your ISP to Google Public DNS. In most cases, the IP addresses used by your ISP's domain name servers are automatically set by your ISP via the Dynamic Host Configuration Protocol (DHCP). To use Google Public DNS, you need to explicitly change the DNS settings in your operating system or device to use the Google Public DNS IP addresses. The procedure for changing your DNS settings varies according to operating system and version (Windows, Mac or Linux) or the device (computer, phone, or router). We give general procedures here that might not apply for your OS or device; please consult your vendor documentation for authoritative information. Note: We recommend that only users who are proficient with configuring operating system settings make these changes. Important: Before you startBefore you change your DNS settings to use Google Public DNS, be sure to write down the current server addresses or settings on a piece of paper. It is very important that you keep these numbers for backup purposes, in case you need to revert to them at any time. We also recommend that you print this page, in the event that you encounter a problem and need to refer to these instructions. Google Public DNS IP addressesThe Google Public DNS IP addresses (IPv4) are as follows:
The Google Public DNS IPv6 addresses are as follows:
You can use either number as your primary or secondary DNS server. You can specify both numbers, but do not specify one number as both primary and secondary. You can configure Google Public DNS addresses for either IPv4 or IPv6 connections, or both. Changing your DNS servers settingsBecause the instructions differ between different versions/releases of each operating system, we only give one version as an example. If you need specific instructions for your operating system/version, please consult your vendor's documentation. You may also find answers on our user group. Many systems allow you to specify multiple DNS servers, to be contacted in a priority order. In the following instructions, we provide steps to specify only the Google Public DNS servers as the primary and secondary servers, to ensure that your setup will correctly use Google Public DNS in all cases. Note: Depending on your network setup, you may need administrator/root privileges to change these settings. Microsoft WindowsDNS settings are specified in the TCP/IP Properties window for the selected network connection. Example: Changing DNS server settings on Microsoft Windows 7
Mac OS XDNS settings are specified in the Network window. Example: Changing DNS server settings on Mac OS 10.5
LinuxIn most modern Linux distributions, DNS settings are configured through Network Manager. Example: Changing DNS server settings on Ubuntu
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
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
RoutersEvery 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:
Mobile or other devicesDNS 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:
Testing your new settingsTo test that the Google DNS resolver is working:
* Google thanks MIT for granting permission to use this URL for the purposes of testing web connectivity. Diagnosing resolution problemsIf you are encountering problems when resolving particular names, and want to verify whether the problem is with Google Public DNS, please try running the following diagnostic procedures. If you want to report a problem to the Google Public DNS user group, please copy and paste the results of the commands in your email. This information is vital to help us to identify the cause of the problem. Step 1: Verify that your client can communicate with the Google Public DNS serversIPv4Open a command prompt, and run the following command: On Windows: tracert -d 8.8.8.8 On Mac OS X: /usr/sbin/traceroute -n -w 2 -q 2 -m 30 8.8.8.8 On Linux: sudo traceroute -n -w 2 -q 2 -m 30 8.8.8.8 If the last line of the output does not list 8.8.8.8 as the final hop, or if there are significant timeouts, there may be a network problem preventing you from contacting our servers. Please include the output of the command in any communication with the Google Public DNS team. If the last line of the output does list 8.8.8.8 as the final hop, continue to step 2. IPv6Open a command prompt, and run the following command: On Windows: tracert -d 2001:4860:4860::8888 On Mac OS X: /usr/sbin/traceroute6 -n -w 2 -q 2 -m 30 2001:4860:4860::8888 On Linux: sudo traceroute -n -w 2 -q 2 -m 30 2001:4860:4860::8888 If the last line of the output does not list 2001:4860:4860::8888 as the final hop, or if there are significant timeouts, there may be a network problem preventing you from contacting our servers. Try configuring Google Public DNS for IPv4 to diagnose whether the problem is due to IPv6 connectivity on your network. If IPv4 works for you, you may want to revert your IPv6 configuration and use Google Public DNS with IPv4 exclusively. Otherwise, please include the output of the command in any communication with the Google Public DNS team. If the last line of the output does list 2001:4860:4860::8888 as the final hop, continue to step 2. Step 2: Verify that Google Public DNS can resolve the selected hostnameIPv4At the command prompt, run the following command, replacing On Windows: nslookup -debug www.google.com. 8.8.8.8 On Mac and Linux: dig @8.8.8.8 www.google.com. If the output shows an answer section with an A record for the hostname, then Google Public DNS is able to resolve the name. Check your settings to make sure your system is correctly configured to use Google Public DNS. If you are still unable to solve the problem, please include the output of the command in any communication with the Google Public DNS team. If the output does not show an answer for the hostname, continue to step 3. IPv6WindowsAt the command prompt, run the following command, replacing nslookup -debug -type=AAAA www.google.com. 2001:4860:4860::8888 If the output shows an answer section with an AAAA record for the hostname, then Google Public DNS is able to resolve the name. Check your settings to make sure your system is correctly configured to use Google Public DNS. If you are still unable to solve the problem, please include the output of the command in any communication with the Google Public DNS team. If the output shows an answer section with an A (IPv4) record for the hostname, then Google Public DNS is able to resolve the name, but the host and/or its nameserver are not configured to return IPv6 results. If you want to verify that you are correctly receiving AAAA records, you can use the hostname If the output for On Mac and LinuxAt the command prompt, run the following command, replacing dig @2001:4860:4860::8888 www.google.com. AAAA If the output shows an answer section with an AAAA record for the hostname, then Google Public DNS is able to resolve the name. Check your settings to make sure your system is correctly configured to use Google Public DNS. If you are still unable to solve the problem, please include the output of the command in any communication with the Google Public DNS team. If the output does not show an AAAA record for the hostname, this may be because the the host and/or its nameserver are not configured to return IPv6 results. If you want to verify that you are correctly receiving AAAA records, you can use the hostname If the output for *Note: Google properties will not return AAAA records for all users. Please see the Google over IPv6 page for more information about whether your system qualifies. Step 3: Verify that another open resolver can resolve the selected hostnameAt the command prompt, run any one of the following commands, replacing www.google.com. with the name that you were having difficulty resolving (still putting a period at the end of the name to avoid problems with domain suffixes and search lists): nslookup www.google.com. 4.2.2.1 nslookup www.google.com. 4.2.2.2 nslookup www.google.com. 208.67.222.222 nslookup www.google.com. 208.67.220.220 (The first two commands test Level 3's DNS servers. The last two commands test OpenDNS' DNS servers.) If you are not able to get a successful result, this means that there is most likely a problem with the server you are trying to contact. Wait some time and try running the tests again. This may be a temporary problem on the server's side that will likely resolve itself eventually. If it does not, you should contact the owner of the server. If you do get a successful result, there may be a problem with Google Public DNS. Please include the output of this command and the one from step 2 in any communication with the Google Public DNS team. Step 4: Check to see if the authoritative nameservers are correctIf Google Public DNS (or any open resolver) has trouble resolving a site, or returns inconsistent answers, sometimes it's because the authoritative nameservers are having trouble. There are various tools and sites to help you check this. Some users (and some Google Public DNS engineers) have found intoDNS to be very helpful. For example, if you're trying to resolve Google thanks the intoDNS staff for letting us link to them. Switching back to your old DNS settingsIf 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. | |
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