Unable to resolve DNS after 10.9.5 update

From the menu bar, select

 ▹ System Preferences... ▹ Network ▹ Advanced... ▹ DNS

Under DNS Servers you should have one or more numerical addresses, such as “192.168.1.1” or “10.0.0.1”. What are those addresses?

Double-click anywhere in the line of text below on this page to select it, then copy it to the Clipboard by pressing the key combination command-C:

www.google.com

Launch the Network Utility application.

Step 1

Select the Lookup tab and paste into the address field by pressing command-V. Then press return. Post the output that appears below – the text, please, not a screenshot.

Step 2

Select the Ping tab and do the same. Please enter the same input as you did in Step 1. Don't use the output of Step 1 as input to Step 2.

Important Note

Some web browsers and mail clients will automatically convert a domain name such as "www.example.com" to a clickable URL, such as http://www.example.com. That will interfere with the test. If necessary, edit the input in the Network Utility window to remove any added characters.

Start up in Recovery mode. In the OS X Utilities screen, select Get Help Online. A clean copy of Safari will launch. No plugins, such as Flash, will be available. While in Recovery, you'll have no access to your saved bookmarks or passwords, so make a note of those before you begin, if they're needed for the test.

Test. After testing, restart as usual and post the results.

If you don't already have a current backup, back up all data, then reinstall the OS.* You don't need to erase the startup volume, and you won't need the backup unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.

If you use FileVault 2, then before running the Installer you must launch Disk Utility and select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another icon with the same name. Click the Unlock button in the toolbar and enter your login password when prompted. Then quit Disk Utility to be returned to the main Recovery screen.

There are ways to back up a computer that isn't fully functional. Ask if you need guidance.

If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.

*The linked support article refers to OS X 10.9 ("Mavericks"), but the procedure is the same for OS X 10.7 ("Lion") and later.