Back up all data.
Unlock the Network preference pane, if necessary, by clicking the lock icon in the lower left corner and entering your password. Cllck Advanced, open the DNS tab, and change the server addresses to the following:
8.8.8.8
8.8.4.4
That's Google DNS. Click OK, then Apply.
In Safari, select
Safari ▹ Preferences... ▹ Privacy ▹ Remove All Website Data
and confirm. If you’re using another browser, empty the cache. Test. Any difference?
Notes:
1. If you lose Internet access after making the above change to your network settings, delete the Google servers in the Network preference pane, then select the TCP/IP tab and click Renew DHCP Lease. That should restore the original DNS settings; otherwise restore them yourself. Remember that you must click Apply in order for any changes to take effect.
2. I don't use Google DNS myself, though I have tested it, and I'm not recommending it or any other DNS provider; the server addresses are offered merely for testing purposes. There may be privacy and technical issues involved in using that service, which you should investigate personally before you decide whether to keep the settings. Other public DNS services exist.
