Practical Networking

In this course, you'll get a practical, hands-on understanding of how to troubleshoot network-related issues. You'll learn all about IPv4 and IPv6 network connectivity, how devices connect to the Internet, how data gets from end to end, how to read a network topology diagram, and more. We also cover specific network troubleshooting techniques and commands including ping, tracert, netsh, ipconfig, and netstat.
Course info
Rating
(899)
Level
Beginner
Updated
Apr 30, 2015
Duration
3h 26m
Table of contents
Introduction to Internetworking
Understanding Internet Connectivity
Network Troubleshooting Methodology
Troubleshooting Physical and Layer 2 Connectivity
Troubleshooting IP Connectivity
Troubleshooting Applications and the Transport Layer
Isolating Problem Scopes and Causes
Web Browsers and HTTP/HTTPS
Troubleshooting Network Latency
Description
Course info
Rating
(899)
Level
Beginner
Updated
Apr 30, 2015
Duration
3h 26m
Description

In this course, you'll get a practical, hands-on understanding of how to troubleshoot network-related issues. You'll learn all about IPv4 and IPv6 network connectivity, how devices connect to the Internet, how data gets from end to end, how to read a network topology diagram, and more. We also cover specific network troubleshooting techniques and commands including ping, tracert, netsh, ipconfig, and netstat.

About the author
About the author

Ben Piper is an IT consultant and the author of "Learn Cisco Network Administration in a Month of Lunches" from Manning Publications. He holds numerous certifications from Cisco, Citrix, and Microsoft.

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Section Introduction Transcripts
Section Introduction Transcripts

Troubleshooting IP Connectivity
In this module we're going to look at troubleshooting IP connectivity. As you remember, IP or the internet protocol, operates at the layer 3 of the OSI model. We are still going to continue to troubleshoot IP connectivity in later modules as well, but we're going to start here with what looks like a simple trouble ticket from Noah Harper. Noah Harper, another user in the headquarters location, says he just got back from vacation and is suddenly unable to access the intranet site. But he can still access the internet. He says that nobody else around him is having a problem. So let's go ahead and take our network topology diagram out again and get a lay of the land. Noah, as we can see, is connected to switch 1 and he has two IP addresses configured. An IPv4 address and an IPv6 address.

Troubleshooting Applications and the Transport Layer
Many applications depend on reliable network transport in order to work properly. The application we've been working with, in Netluxia's environment, has been the internal intranet site, which runs on a server in the branch office. Up to this point we've been focusing on the basic IP network connectivity using things like ping and trace route to determine whether the site is reachable. But practical networking involves more than just pings and trace routes. As a network support administrator, you need to understand the relationship between applications and the transport layer, layer 4.

Isolating Problem Scopes and Causes
We just got word from Netluxia's network team that David's problem with not being able to access the intranet site over port 443, HTTPS, has been resolved. They told us that the problem was that R3 was blocking any packets from the VPN network that were destined for TCP port 443. This makes sense because David was still able to access the site of report 80, but not port 443. But David's troubles aren't over quite yet. We just got another ticket from him saying that he still cannot get to the intranet. He's getting a strange message that there is a problem with the website security certificate. So we called David up to confirm that the problem is still happening and to get little bit more detail. Hi David, can you tell me a little bit more about what's happening now? And David says, well someone from the network team called me and said they resolved my problem, and that I needed to start using HTTPS to get to the intranet site. So I tried that, I just put HTTPS instead of HTTP in Internet Explorer and then I got an error. So we say, now just to confirm David, can you please tell me the error message you're seeing? And David says, well sure it says there's a problem with the website security certificate. So before we get on David's computer, let's talk a little bit about this security certificate that Internet Explorer is referring too.

Web Browsers and HTTP/HTTPS
So far we've gone all the way from the physical layer of the OSI model, layer 1, to layer 5, the session layer. Now we're going to focus on a couple of specific applications that operate at layer 7, specifically HTTP and HTTPS. HTTP, or hypertext transfer protocol, is the protocol that websites use to deliver data. For example, web pages to a web browser. We're not going to be doing any packet captures or dealing directly with the technical specifics of HTTP, because those fall outside the scope of practical networking. Instead we're going to be focusing on web browsers and how they're used in organizational environments. The specific data or code that web server send is called HTML or hypertext markup language. Now I want to emphasize that HTML is not the only data that is sent to a web browser, there's also JavaScript, binary files like pictures and videos and so on. But in this module we're focusing on the web browser experience and not digging into the details of each and every protocol.

Troubleshooting Network Latency
In this module we're going to learn how to diagnosis and troubleshoot network latency. One common complaint you may have heard or perhaps have even made yourself is, the network is slow. Network latency simply means the network either is or just appears to be operating more slowly than normal, but network latency is the symptom, not a cause. So just as with any other problem, we have to diagnosis and troubleshoot to get to the root cause of the preserved network latency. Now before we start, let me give you a quick warning. Network latency problems are sometimes difficult to troubleshoot even for experienced network engineers. In your position as a support administrator, you should not be expected to resolve every network latency issue. But you will need to be able to at least help diagnosis the cause. And that's exactly what we're going to do right now in this module. Let's go ahead and take a look at our next ticket from Paul. Paul says he cannot get to the intranet site again and he's getting a page cannot be displayed error. We also have another ticket from Noah that says the intranet site takes a very long time to load. Might these two tickets be related? Well we're going to tackle both of these tickets and find out for sure.