What is the difference between a forward proxy and a reverse proxy?
What they are really testing: Whether you understand which side each one represents. People mix these up constantly, and reverse proxies are everywhere in cloud (load balancers, API gateways, ingress).
A real interview question
What is the difference between a forward proxy and a reverse proxy?
What most people say
drag me
“A proxy sits in the middle and forwards traffic between the client and server.”
It describes "a proxy" generically and never distinguishes the two. The whole question is which side it fronts, and the answer does not pick a side.
The follow-ups they ask next
Is an application load balancer a forward or reverse proxy?
Reverse: clients connect to it as if it were the service, and it distributes to backends, often terminating TLS and routing by path.
Why put a reverse proxy in front of your app at all?
Central TLS termination, load balancing, caching/compression, path/host routing, and not exposing backend IPs, all in one place instead of in every app.
What the interviewer is listening for
- Frames it as which side it fronts
- Gives correct use cases for each
- Knows cloud LBs/ingress/CDN are reverse proxies
What sinks the answer
- Describes "a proxy" without distinguishing
- Swaps the two
- Thinks a load balancer is a forward proxy
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“It is about which side it fronts. A forward proxy [sits in front of clients and requests outward for them, so the server sees the proxy], used for [egress control, filtering, caching]. A reverse proxy [sits in front of servers and accepts requests for them, so the client thinks it is the server], used for [TLS termination, load balancing, routing]. In cloud, [load balancers, ingress, CDNs are reverse proxies].”
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