Go straight to the Change Log to see what's new since June 2011

Want to change your DNS server? You might need to know more about What DNS Servers Do or you might need to know How to Find the Best DNS Server.

There are three sections in this how to guide.

1. Why change my DNS Server?
2. How is your system configured for DNS
3. How to change your DNS settings

For speedy performance

Every web page requires an IP address before it can be loaded. The time taken to resolve a DNS name can add several seconds to the loading of a page. The faster your DNS server then the quicker your pages will load.

The larger the database of the DNS server then the greater the likelihood that the name will be found without searching on other DNS servers. These cached hits are much faster than uncached hits. Typically by a factor of ten so a 0.1 second.cached name could take 1 second if it is not found in the DNS server database.

For increased reliabilty

Most DNS servers are available near enough to 100% of the time. If your isn't then find a more reliable server. DNS queries can timeout or, in the worst case, receive no response at all. There are several ways to reduce such problems:

• Your primary DNS server should be the fastest DNS server for you.
• Define more than one DNS server to use - a minimum of two and probably more - to reduce the risk of one or more DNS servers not being available.
• Use DNS servers that are in different cities or countries, ie geographically diverse, to reduce the likelihood that one 'disaster' will affect all your DNS servers at the same time.
• Have at least one DNS server that is close to your location, probably a DNS server at your Internet Service Provider (ISP).
• If your ISP is small then definitely look for a DNS server with a larger database.

For greater safety

All DNS servers do not offer the same features or have the same vulnerabilities. Many DNS servers still do not operate using established security features like DNSSEC.

Some DNS servers provide additional features such as the filtering of web addresses to improve security. These solutions can create other problems.:

• Malware protection is provided by Norton DNS and others
• Phishing protection is provided by OpenDNS and others
• Category filtering for parental controls is provided by OpenDNS and others

Configuration

Automatic configuration from your ISP?

You will usually define your DNS servers when you configure your Internet network connection whether dial-up or broadband. Most Internet Service Providers (ISPs) have automatic configuration of some sort so the DNS servers are defined automatically. If you had to manually configure the network connection then chances are that you also had to manually define the DNS servers.

Configuration on your system

DNS servers settings will exist for each PC you use on the Internet whether they were manually input or automatically configured. The key question is where are my external DNS servers defined?

• At your PC? If it is directly connected to a modem for Internet access then it will have the system DNS servers.
• At your router? If you have a local area network (LAN) then a router is usually the best place to define your DNS servers. Any device connected to that router can be updated automatically using the Dynamic Host Configuration Protocol (DHCP). This means that changing the external DNS servers at the router will affect all devices connecting to it using DHCP.
  The problem with this is that cheap home routers can cause problems. This seems to be the case with my router. I have more problems when my router is configured as the DNS Server with the IP address192.168.2.1 (an address reserved for internal networks) than if I define the DNS servers manually at each PC.

How to find your system DNS servers

There are several methods to find your system DNS servers. If you want to know more then go to the next section Changing your DNS configuration for further resources.

1. I recommend that you use the excellent resources for changing your DNS configuration in the next section. The best cover most operating systems and many routers.
2. In your network connection settings, go to the properties for your network connection, select the network card if there is more than one, and then the TCP/IP protocal properties which include the DNS servers..
3. The programs described in How to Find the Best DNS Server will tell you what your DNS servers are.
4. The Windows command line: ipconfig /all displays the system IP configuration including the system DNS servers

Example of method 2 - Inspect your network connection settings in Windows

Note that you can exit out of this by pressing the Esc key, selecting Cancel, or closing each window.

• Find the network connection icon in the system tray at the bottom right of your screen.
  Right click on the network connection icon with your mouse to bring up the context menu.
  Select the 'Status' menu item.

  
• The Local Area Connection Status dialog should display.
  Select the 'Properties' button.

• The Local Area Connection Properties dialog should display.
  Select 'Internet Protocol TCP/IP'

• The Internet Protocol (TCP/IP) Properties dialog should display.
  The DNS configuration is visible at the bottom.
  In this example, the DNS servers have been defined manually but they would not be visible if the radio button was selected for 'Obtain DNS server address automatically'.
  If they are visible, select the 'Advanced' button to see the Advanced TCP/IP Settings where we can see if more than two DNS servers are defined.

  

• The Advanced TCP/IP Settings dialog should display.
  The IP Settings tab will be displayed first.
  Select the 'DNS' tab to display the DNS server addresses. In this example, there are only two DNS servers.
  I have also selected the 'Add' button to bring up the 'TCP/IP DNS Server' dialog in which I've entered a DNS server IP address 8.8.4.4 ready to 'Add'.
  The sort order can be changed using the arrows at the right.

  

How to test if the system DNS configuration is damaged

You can incorrectly configure your system DNS by, for example, typing in incorrect IP addresses for the DNS servers. If you do this then your web browser will not be able to access Internet resources using domain names but you should be able to use URLs with a valid IP address. Just type a valid IP address in as the URL and your browser should add the rest e.g. 72.52.134.16 is converted to http://72.52.134.16/.

If you find you have lost all web access even using IP addresses then that is very unlikely to be a DNS problem. Your network connection could be down or malware could have changed your configuration (e.g. by setting your network connection to use a proxy server).

Before configuring your chosen DNS Servers

You might want to run a DNS Spoof Test to check the vulnerability of your chosen DNS servers. Just be aware that some routers lockup or crash if you run these tests. GRC provides a list of routers with known problems. It didn't include mine which crashed when I tested it. I had guessed it might because it is similar to some of those listed. That's a good reason to get a better router. See GRC's notes at the bottom of the DNS Spoof Test page for a list of routers that fail in this way.

Resources to help you change your DNS configuration

There are programs to automate the changeover to better DNS servers but I'd give them all a miss. Instead, I encourage you to visit some excellent resources that will help you.

Web quides and tutorials

• OpenDNS has an excellent Setup guide for most operating systems. There are video tutorials which some will find useful. DNS Benchmark discusses the issues around router-based DNS configuration. The site also recommends the OpenDNS guide.
• Google has good instructions for both changing and then testing the new configuration.
• Other simpler, less complete guides can be found at DNS Advantage (Comodo DNS). ClearCloud has instructions to switch away it as it is discontinuing its free DNS service.

Software that might help you to change your configuration but are too limited

DNS Jumper will change your DNS addresses for you but has some significant weaknesses:

• Only the first two DNS servers can be changed on your system. If you want more than two then you will need to find another solution.
• By default it only includes public DNS servers in its database. You can add others.
• It can only change to a set of DNS servers e.g. both from Google or both from OpenDNS. If you want to mix service providers then you will have to add a new set yourself.

DNS Helper (formerly Google DNS Helper) is a utility to change to one of the main global DNS service providers that I do not recommend:

• You cannot add your own servers apart from one set of custom DNS servers.
• If you change DNS servers while in a Windows session it will not update the DNS server IPs to restore until you start a new session.

Likewise Public DNS Server Tool is too limited to be recommended.

After you change your DNS configuration

Flush the system DNS caches

When you change your DNS configuration you should clear the system caches so that the new DNS settings take immediate effect. I use CCleaner, the Editor's Choice for Best Free File Cleaner, to clear the caches because it runs once and cleans each browser's cache. Other options are more limited.

• Flush the system DNS resolver cache.
  The Windows command ipconfig /flushdns will flush the DNS resolver cache and refresh it with only the entries in the Hosts file. ipconfig /displaydns will display the system DNS cache.
• Flush your web browser caches
  Some browsers will allow you to do this from the menu.

Using DNS servers for security

• What DNS Servers Do
• How to Find the Best DNS Server
• Best Free DNS Server - coming soon
• Safe Computing in Under an Hour
• How to Block Bad Websites
• Best Free Parental Filter

Products mentioned here

• DNS Jumper: A Quick Way to Change or Check your DNS Setting

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Domain Name System, DNS, DNS server, DNS resolver, DNS resolution, DNS name server, Internet name server, DNS Helper, Public DNS Server Tool, DNS Jumper