ASP.net queue length vs Application Pool queue length

Question

I am looking to to make my web application scalable and was going through articles in which it was said that the queue length should be increased by a factor of say 1.5 * the number of users.

Settings:

1. IIS-> Application Pool Default Settings -> Queue Length

2. IIS ->ASP.NET-> Queue Length

Question: What is the difference between the queue length properties?

I am aware that one says it handles HTTP.sys requests and the other concurrent asp.net requests. However, how will it help an application scale ie will changing only one suffice or both are performing some different role.

Answer 1

The application pool can handle multiple websites, so the queue is for every site inside the pool. The ASP.NET queue is restricted for that website.

Answer 1: Appilcation Pool Default Settings -> Queue Length:

Optional uint attribute.

Indicates to HTTP.sys how many requests to queue for an application pool before rejecting future requests.

When the value set for this property is exceeded, IIS rejects subsequent requests with a 503 error. If the loadBalancerCapabilities setting is true, the connection is closed instead of rejecting requests with a 503.

https://docs.microsoft.com/en-us/iis/configuration/system.applicationhost/applicationpools/applicationpooldefaults/

Answer 2: IIS -> ASP.NET -> Queue Length:

Its the same, but related to the website selected.