One thing you can do if you are having problems with your Mac web browser is clear the DNS cache. So, what exactly is clearing the DNS cache?
A DNS cache or DNS resolver cache, is a temporary database of DNS lookups on the OS and browser. It consists of the records of recent as well as attempted visits of websites along with domains. To troubleshot cache poisoning or other internet connectivity issues, you may need to flush the DNS cache.
That pretty much sums it up. To learn how to do this, just read this article which explains how to Flush the DNS cache on current and older Macs.