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Non-responsive DNS server or invalid DNS configuration can cause long delay before webpages load

Symptoms

When trying to access a website via its DNS name, such as www.apple.com, there may be a delay that ranges from several seconds up to several minutes before the page loads at normal speed, depending on the operating system version and configuration. However, if you access the website's numerical IP address, such as http://17.149.160.49 , the page loads immediately.

Two causes of the issue are described below, DNS configuration and changing networks. Issues related to changing networks usually only affect portable Macs.

Resolution

DNS configuration

This may indicate a non-responsive DNS server or an invalid DNS configuration. A DNS server converts a name to a numerical IP address, "www.apple.com" to "17.149.160.49", for example. You can connect to an IP address without any delay, because the need for DNS resolution is avoided. Here are four scenarios in which the symptom may occur:

  • You have specified two or more DNS servers in the Network preference pane (possibly at the direction of a network administrator or your ISP), but the first server on the list has become non-responsive, or was entered incorrectly. The delay occurs while Mac OS X waits for the first server to respond, then it goes to the next server in your list.  Make sure the addresses are entered correctly. Changing the order of DNS addresses may improve performance. If your network administrator prefers that the primary server be used, you may wish to change back to the original order after the issue is resolved with the primary server.
  • Your network may be configured to provide automatic discovery of DNS service, without needing to manually type the DNS server addresses at your computer. If you have manually typed a DNS address that is incorrect or out of date, your computer may wait for the incorrect address to respond (a "timeout") before succeeding at automatic discovery.
  • You have not specified a DNS server, and automatic discovery of the service is not provided on your network. In this scenario, you can only connect via an IP address. Web pages do not load at all via a DNS name, such as is described in this article.


How to resolve


Check with your network administrator or Internet Service Provider (ISP) to make sure your DNS information is correct. If your ISP only provides you with one DNS address, consider requesting a second one for use in the event that the first becomes unavailable.

Once you have the address(es), you can use these steps to change your DNS information. Note: After using these steps, some Internet applications may need to be quit and reopened to return to normal behavior.

Mac OS X v10.5 or later:

  1. From the Apple menu, choose System Preferences.
  2. From the View menu, choose Network.
  3. Click the interface you use to connect to the Internet, such as AirPort or Built-in Ethernet.
  4. If you use Built-in Ethernet: Type your DNS address(es) in the DNS Server field. If you have more than one, separate them with a comma.
    If you use AirPort, click Advanced, then click the DNS tab. For each server, click the "+" button under DNS Servers and enter the address provided by your ISP or network admin. Click OK when done.
  5. Click Apply.

Mac OS X v10.4 or earlier:

  1. From the Apple menu, choose System Preferences.
  2. From the View menu, choose Network.
  3. From the Show menu, choose the interface you use to connect to the Internet.
  4. Click the TCP/IP tab.
  5. Type your DNS address in the Domain Name Servers field. If you have more than one, press Return at the end of each to put the next address on a new line.
  6. Click Apply Now.


Changing networks

You may experience a delay with the first connection after changing networks on a portable Mac. For example, you might use an MacBook at home with AirPort, then take it to work or school and use an Ethernet connection. By default, Mac OS X uses one set of Internet preferences (known as a "location") named Automatic that will search your computer's modem, Ethernet, and AirPort interfaces until it finds the one that is connected to the Internet. You may experience a delay while your computer determines which network it is on. This can be easily differentiated from a DNS issue by creating a location that only contains one network interface. For more information, see Using network locations in Mac OS X.

Additional Information

Tip: If issues persist after trying the above steps, consider removing any manually-entered DNS addresses from the Network preferences pane. Select the address, then click the minus ("-") button. Note that dimmed addresses cannot be removed.

Last Modified: Sep 11, 2012
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  • Last Modified: Sep 11, 2012
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