5 Replies Latest reply: Apr 1, 2014 7:49 AM by JohnNY123
1technospaz Level 1 Level 1

Disabeling the DNS prefetching didn't solve my problem and now all the sites load slowly. How do i re-enable DNS prefetching through the terminal window. These were the original instructions:




Mac OS X steps to disable DNS prefetching

          1.          Open Terminal (in /Applications/Utilities).

          2.          Execute the Terminal command below to disable DNS prefetching:
defaults write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false


Any help/advice appreciated!

Solved by Linc Davis on Jan 2, 2013 10:20 AM Solved
See "Steps to re-enable DNS prefetching in Mac OS X" in the article.
  • Linc Davis Level 10 Level 10

    See "Steps to re-enable DNS prefetching in Mac OS X" in the article.

  • 1technospaz Level 1 Level 1

    Thanks. I COMPLETELY missed that! All re-enabled now.

    : )

  • JohnNY123 Level 1 Level 1

    Hi Linc,


    I tried using the command:


    defaults delete com.apple.safari WebKitDNSPrefetchingEnabled


    ....in a Terminal window to re-enable DNS prefetching and I got this message after hitting enter:


    2013-11-18 20:21:24.479 defaults[359:507]

    Domain (com.apple.safari) not found.

    Defaults have not been changed.


    Any idea what this means?  Am I to assume that because of this error that DNS prefetching has not been re-enabled correctly?




  • RCully Level 1 Level 1

    John, Did you ever get an answer to this as I am getting the same response (after following Apple instructions).


    I continue to get very slow responses on Safari (both iMac and MBA) - it looks like slow DNS lookups but after trying all sorts, it's still there.

  • JohnNY123 Level 1 Level 1

    Hi RCully....


    No, I never did get an answer.........I kind of dropped the pre-fetching topic on my side because whether it was on or off, it didn't seem to make a tremendous difference on my browsing speed.


    My browsing/page-loading problem actually ended up being something with my Comcast cable provider, and also an update to my antivirus software that I didn't notice come through that had an option defaulted to 'on' to check every URL on every web page against a suspecting phishing URL list.  You can imagine the performance degradation from that AV option!  So....I shut that AV option off and it dramatically improved my browsing speed overall, right back to where it was before.