Moderate WebSockets Question 130 of 226

Why does Socket.IO fall back to HTTP long polling?

MERN Full Stack · Speak this in 60–90 seconds · Faridabad & Delhi NCR

ClientGET /users/1

ServerFind row

JSON back200 OK

Some proxies, firewalls, or old browsers block the WebSocket upgrade.

Why interviewers care about WebSockets:

They are checking judgment

on WebSockets.

A good answer names

the situation, the default choice, and one exception - that reads as experience.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
Some proxies, firewalls, or
old browsers block the WebSocket upgrade.
2
Long polling keeps the
app working with repeated HTTP requests.
3
You still design events
as if the transport might be slower and less efficient.
4
Give an example
One tiny concrete case you can say aloud.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“Long polling keeps the app working with repeated HTTP requests.”

Break into beats

Longpollingkeepstheappworking

Speaking order

2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Some proxies, firewalls, or old browsers block the WebSocket upgrade. Long polling keeps the app working with repeated HTTP requests.