checklist

Could identify private IPs and public IPs.

Know why DNS and NTP are based on UDP.

(Optional) Know the websocket and the scenario that we use it.

(Optional) Know how CGI works.

Know CDN works and distribute files. And how to avoid cache when requesting files from CDN.

(Optional) Know what AJAX and JSONP are. Know how to resolve CORS problems.

(Optional) Know how TCP validates data, identifies and retransmits missing packets and congestion control.

(Optional) Know what MTU, RTO, MSS, MSL mean in TCP.

(Optional) How to transfer a big file via TCP or UDP?

(Optional) Know the differences and disadvantages between LVS(ipvs) working modes.

(Optional) Know what TIME-WAIT state means in a TCP connection and how to avoid