Example of 4-Tier (for N-Tier) Architecture?

Question

Recently a friend of mine asked me about N-Tier architectures and I was able to explain to him about 1, 2 and 3 tier architectures with examples. But I was stuck when I wanted t

Answer 1

A four tier architecture consists of the following

a. client tier -- node.js angularJs, etc basically independent of server side and UI team work on the client artifact independently

b. Aggregation tier --- content delivery networks (akamai)

c. api tier -- gateway for all the server side calls and can have its own caching

d. services tier -- includes internal or external services...