F#: Checking if a specific URL returns an HTTP 404 Error

I am new to programming and F# is my first language. I am currently still very unfamiliar with .NET APIs.

I would like to write a function that, given a specific URL, tests whether it returns an HTTP 404 Error.

I have looked through the System.NET namespace, but I am at a loss regarding which classes/methods to use. Specifically, I have looked at the WebClient, WebRequest and WebResponse classes, but I don't know which one is appropriate.

Any advice would be appreciated. Thanks.