Why is Quora not working?

When you try to load a page, the browser goes to a Domain Name Server (DNS) to get the Internet Protocol Address (IPA) of the site you asked for. That is because the internet uses a number to identify the actual location for each site, not the name you are familiar with. If that stops working you get "DNS failure".

The internet is a collection of networks, so your request must be routed through gateways connecting one to the next. Sometimes a gateway gets bogged down and it takes a moment to clean itself out and start fresh. Then you get a Gateway Timeout.