Web servers, and servers in general, are prone to breakage, just like any other machine. Troubleshooting a web server can involve lots of different variables. We won't discuss a specific troubleshooting scenario in this lesson, but we'll talk about some easy trouble shooting tools you can use to diagnose a faulty web server or browser called HTTP status codes. When we want to go to Google.com our browser is sending an HTTP request to the HTTP server on the web server. In turn we get an HTTP response. Sometimes this response returns the content that we want. Almost all the time it'll return a status message of the response. HTTP status codes are codes or numbers that indicate some sort of error or info messages that occurred when trying to access a web resource. Knowing common HTTP status code comes in handy when you're troubleshooting website error. They usually tell you useful information that can help you isolate the root cause. Here's a common HTTP status code you might recognized. The dreaded 404 Not Found A 404 error indicates that the URL you entered doesn't point to anything. Let's see what happens if I type in google.com/asdf, let's type that in. I get this error message. The requested URL /asdf was not found on this server. That is exactly what I expected to happen. I typed in an address, I knew didn't exist and the website confirmed it for me. But, how do we know it is a 404 error code? Depending on the website HTTP error messages could be displayed right on the page when you try to access it. However, to be absolutely sure you can just view the HTTP response itself. To do that we'll have to do a bit of work. Browsers today have built in tools that help people diagnose issues with the web browser or website itself. Since I'm using Chrome, I'm going to use a Chrome Developer Tools, let me go ahead and do that. So, I want to click on this, I get into tools. And then click on Developer Tools. This will open up the Developer Tools side by side to my web browser. Developer Tools is a great resource for testing and debugging issues with the website or browser. We won't go through this tool, though. If you want to learn more, you can check out the supplemental reading. For now, we just want to see the HTTP response code. To get to that, I'm going to go to the network type here and refresh my page. If I'm trying to go to google.com/asdf, I'll see the request I made in the left hand side here. If I clicked that, I'll see the status codes says 404 not found, pretty me, right? HTTP status codes that start with 4xx indicate an issue on the client-side. The client try to do something that it couldn't, like enter a bad URL. Access something it was not authorized to do, etc. The other common HTTP status codes that you might see start with 5xx. These errors indicate an issue on the server-side. The web server that hosts this web content is experiencing issues and hopefully their server administrators are looking into it. HTTP status codes tell us more than just errors. They can also tell us when our request is successful, which is denoted by the codes that begin with 2xx. HTTP status codes can tell us a lot about an issue with a website. If you encounter one you aren't familiar with, just look it up. They will probably tell you exactly what the issue is. For a list of HTTP status code, take a look at the supplemental reading. Well, you have done it again, you have covered a lot of information in this module about software and platform services. You learned about IT infrastructure services that help a business stay productive, like communication services. You learned about security services that keep information secure between web browsers and servers. You also learned about platform services that are used to deliver applications to users. Now, you can put that knowledge to the test in a short test we've cooked up for you. In the next module, we'll talk about managing users, computers, and policies, using directory services. You're doing an awesome job, I know covered a lot but stick with it you got this.