Angular 2 Hosted on IIS: HTTP Error 404

 We have to make IIS fall back to index.html by adding a rewrite rule.

Step 1: Install IIS URL Rewrite Module

Step 2: Add a rewrite rule to web.config

   <?xml version="1.0" encoding="utf-8"?>
    <configuration>
      <system.webServer>
        <rewrite>
          <rules>
            <rule name="AngularJS Routes" stopProcessing="true">
              <match url=".*" />
              <conditions logicalGrouping="MatchAll">
                <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />   
              </conditions>
              <action type="Rewrite" url="/" />
            </rule>
          </rules>
        </rewrite>
      </system.webServer>
    </configuration>

STEP 3: add web.config link to angular.json: (because after ng build it will skipped)
"architect": {
                "build": {
                    "builder": "@angular-devkit/build-angular:browser",
                    "options": {
                         ..........
                        "assets": [
                            "src/favicon.ico",
                            "src/assets",
                            **"src/web.config"**
                        ]