You don't have permission to access "http://www.zappos.com/" on this server.

Clear Safari's website data and / or history:

Clear your browsing history in Safari on Mac - Apple Support

• You can clear all history or just the past hour, day, etc.

Manage cookies and website data in Safari on Mac - Apple Support

• Type Zappos in its Search field or just Remove All. The latter will cause you to be logged out of websites that require logins (like this one) so you will have to log in again.

That should fix it.

For those of you where it is not working are you behind a vpn, corporate, educational, firewall?

Are you using proxy connections in your networking preferences?

Are you using any custom DNS addresses in your network preferences?

Did the DNS addresses come from your internet provider or someone else?

No issue here using your provide link above

Try https://www.zappos.com/

FWIW, http://www.zappos.com/ & https://www.zappos.com/ are not the same thing.

Have you tried a different browser?