After switching to load-balanced servers, Restart is required to see new content after TFS Build agent deployment - why?

Question

User1164381444 posted

I've been deploying my project via a TFS build agent for over a year.

After deploying, navigating to the server would display the changes without any intervention with the servers.

Recently, we switched to a load-balanced environment.

After running the build agent, the site does not reflect the changes.

In order to make changes are displayed to site visitors, I've been RDPing to each load balanced server and using IIS Manager to restart the server (Select server, right panel labled Actions, Manage Server section, Restart link).

I have two questions:

1. Why is this added step suddenly required in a load-balanced environment?
2. Should the issue be addressed via modifying the build agent, or do we need to change the server settings?