Network Software Issues

Name: Network Software Issues
Author: Matthew Mercaldi

Learn about logical networking issues

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Course: On-Demand

Hello, in this lesson, we'll be going over the Dynamic Name System. So, what is the Dynamic Name System, or DNS, as you may already know it as? Well, DNS maps hostnames and fqdns to IP addresses. Fqdn, by the way, is fully qualified domain name. One example of what a DNS, or a DNS hostname is, is google.com. You ping google.com, you get an IP address. Your DNS server, whatever you use, could be a public one, could one distributed by your ISP, could be one that your company sets. They are all responsible for mapping host names to IP addresses. With DNS, you have A records and CNAMEs. So, your A record would be your host name itself mapped into an IP address. So, on a public DNS, it would be like, google.com mapped the IP address. On a local DNS, so if you're a part of a whole corporate infrastructure, your company most likely has their own internal DNS server. Your PC has an A record on that DNS server, or at least it should. CNAMEs maps a hostname to another hostname. So, they share the same IP address. It just gets mapped. There's various scenarios in which you would want to do this. So, one use case would be if you have two web servers, web1.company.com as a primary, web2.company.com as a backup, a CNAME would be web.company.com, pointing to web1, and web2 would be a failover. Issues. So, one common issue is DNS names not configured properly on the registrar site, or DNS server. So, this actually happens quite a bit. Usually, it's a fat finger, or the IP address doesn't exist, or the server itself was down, or it was restored from a backup, even, and the backup was incomplete, or not up-to-date. DNS server is not been configured properly or not updating. So, one common thing I see with the DNS server not being configured properly, is it's missing reverse lookup zones, or even some cases the forward lookup zones, or the forward lookup zones are not updating properly. Now, you actually see the forward lookup zones not updating properly on public cloud DNS, such as if your company's using Azure DNS, or maybe AWS DNS. But I know for a fact Azure DNS does this, where it just doesn't update your computers on the forward lookup zone. So, for this lab, we'll be utilizing PowerShell to test out everything DNS related. We'll just dive right into a common issue that might come up in which maybe a vendor that you are trying to connect to, we'll just say KnowledgeCity, for example. They have multiple sites they're using like a F five appliance in which it hosts its own A records, and you could actually set which region of the country goes to which web server. Well, first we should check out what our actual DNS server is. So, you do that by going to ipconfig/all. And right here, we see our DNS servers, internal DNS server 10.50.0.1. Obviously, if KnowledgeCity does not load, it could actually be due to A not having a DNS, or you having the incorrect DNS. Next is let's make sure that we are getting the correct IP address for KnowledgeCity. According to my computer, we're getting 52.89.129.183. Now ping is not being, we're getting request timeout, but that could just be due to security that's built into this. Now, we could try a couple other ping commands. One of which would be ping-A, and we do the IP address. Ping-A is a reverse DNS, and we'll actually to the DNS table to find what the IP address is of the site. Now, the problem with that is only works for A records. And if knowledgecity.com was a CNAME, it wouldn't work. It'll bring up some A record. Also, you may get different output if this site is hosted with AWS, or Azure, or certain other, or Cloudflare, possibly as well. So you have to use that with a grain salt. But the big thing would be, actually, nslookup. So for here, we can actually do multiple things here. So first, I would just type in knowledgecity.com. And here, we're getting an IP address that we always got. But let's say we wanna change DNS servers just for kicks, let's see what could, what other output we might get. So here, we would actually type in knowledgecity.com, and we would then type in what other DNS server we want test out. So we'll test out 8.8.8.8. We'll also test out, I believe, Level three's DNS which is 4.2.2.2. And right here, we see that we're getting the same IP address all across the board. Now, if we were to put in, if we're in a large company, and we have multiple different DNS servers, like I said, and we want to sell access from, like, England, or access from China, for example, we would actually, well we would route everything out but we would also want actually test out the DNS. And this is the way you would test out the DNS utilizing NS lookup. That's it for this lesson. Thank you for (indistinct).

Intermediate Provider : Matthew Mercaldi 3 Lessons · 16m in Arabic, German, English, Spanish, French, Portuguese, Chinese

Course Description

In this course, you will learn about how logical components of applications can affect network connectivity. We will discuss SSL certificates and how they affect different web applications and websites, as well as how to download certificates, identify bad certificates, and determine where to find new certificates.

You’ll learn how to properly configure a firewall to protect your network’s traffic without blocking out important sites or applications you want to remain available. We’ll also cover how troubleshoot any issues your firewall may be causing. By the end of this course, you’ll be able to properly diagnose any connectivity issues caused by software conflicts, discover the underlying cause, and determine the best means of addressing it.

What You'll Learn

Understand the Dynamic Domain Name System (DNS) and how it affects network connectivity
Configure firewalls to function with your network without blocking important sites or applications
Identify what SSL certificates are, how they affect web applications and websites, and how to find them
Download certificates, identify bad certificates, and determine where to find new certificates
Troubleshoot issues your firewall may be causing
Diagnose connectivity issues caused by software conflicts and determine the best way to address them

Key Takeaways

The logical components of applications can affect network connectivity.
SSL certificates affect different web applications and websites, and the course covers how to download them, identify bad ones, and find new ones.
A properly configured firewall protects network traffic without blocking out important sites or applications you want to remain available.
Firewalls can cause connectivity issues, and the course covers how to troubleshoot them.
By the end of the course, you can diagnose connectivity issues caused by software conflicts, find the underlying cause, and determine how to address it.

Frequently Asked Questions

What does this course cover?

It covers how logical components of applications can affect network connectivity, including SSL certificates and how they affect web applications and websites, how to configure a firewall to protect your network's traffic without blocking important sites or applications, and how to troubleshoot firewall issues. The lessons are Dynamic Name System (DNS), SSL Certificate, and Security.

What will I be able to do after completing this course?

You'll be able to properly diagnose connectivity issues caused by software conflicts, discover the underlying cause, and determine the best means of addressing it.

What will I learn about SSL certificates?

You'll learn what SSL certificates are and how they affect different web applications and websites, as well as how to download certificates, identify bad certificates, and determine where to find new certificates.

What skills does this course help build?

It builds skills in Network Connections, Network Diagnostics, Network Support, Network Utilities, and Network Technical Support Certification.