Command Line Tools for Diagnosing Network Issues1 H 57 M
Every IT technician will have to deal with network issues from time to time. In this course, learn how to assess and resolve common network problems.
- Networking Troubleshooting
- Troubleshooting with CMD
- Troubleshooting with CMD Part 2
- Setting IP Information
- Setting IP Information Part 2
Troubleshooting with CMD
- Episode Description
In this episode, Daniel and Wes show you how to troubleshoot common network issues using command line tools. Specific tools covered include ipconfig, ping, and tracert.
[MUSIC] All right, greetings everyone, and welcome to another great episode of ITProTV. I'm your host, Daniel Lowrie, and in today's episode we are taking a look at network troubleshooting. Joining us today to help us out with that very endeavor, is none other than our good friend, Mr. Wes Bryan. Wes, welcome to the show, sir. How's it going? >> It's going great, and as always, Dan, it's great to be back here. And that's right, we're gonna look at a little bit of the command line and see what we got going on when it comes to the world of troubleshooting. So, tell you what, let's go ahead and dive in. And Dan, one of the first commands I think when I think of just understanding about the networking communications in general, is gonna be good old trusty ipconfig. Now, we've probably seen this before in other episodes and if you haven't, well, that's good that you're here. We gotta keep in mind that we got a lot of good episodes on networking that can show you really in depth about ipconfig. So what is ipconfig for us? Well that's the internet protocol configuration utility. And what we use it for primarily is to look and see the parameters, TCP/IP parameters of our network adapter. Now let's take the geek speak and all the acronyms and alphabet soup out of it. What does that mean for us? Well, we have to have an IP address, right, to communicate across the TCP/IP based network. So this is one of the first utilities that lets us know well, what are those settings, Dan? So I think we'll just go ahead and dive right in here and see what we have. So I've got a command prompt pulled up and I'm just gonna type ipconfig. Now if I just type ipconfig by itself it's gonna give me some basic information. Now you have to pay attention to which network adapter you have, and it starts to get a little confusing sometimes when you couple in things like maybe wireless adapter and a wired adapter, and then Bluetooth. And you should see some IPv6 here going on, Toredo and some of those other adapters and technologies that are out there. The ones that we really are concerned with, specifically in a TCP/IP v4 network, is gonna be the one that you see right here. And if you notice, we have what? We have our Ethernet adapter Ethernet0. Right, Ethernet0 is the name of the local area connection. Now you might, out there, look and see local area connection. Right, that's pretty standard here. Now, I'm in a virtual machine. So, kind of renames the network virtualized adapters a little bit differently, but that's all it is, it's just a name. It's gonna look maybe the local area connection for you. Now Dan, one of the first things I have to find out is if I do have network connection problems, right? If I don't have communication, right? I'm gonna probably check here, right? I'm probably gonna check the IP address cuz I have to have one. Now Dan, you mentioned something earlier, right? If we are gonna check for network communications, ipconfig might not be the first place I go, right? >> Yeah, usually it's really a good idea to actually check your cable stuff first. It happens all the time. No, that's not specifically a command line function, obviously we're in the physical realm and that's kind of a virtual thing, digitized, as it were. But it does happen a lot, maybe you moved your desk, maybe you said, you know what, my computer would look better over here or it'd be more functional. And now I got a different office, awesome, I'm migrating over there for all my stuff, and you forgot to plug that cable in. That is one thing that'll stop you dead in your tracks every time, you're not gonna get much connectivity if your cable isn't actually plugged in. Might be on a wireless network, that could happen, right? But if you are on a wired network, check both ends of the cable, right, make sure that they are securely seated, listen for that click, and then if you're still having trouble, just make sure that there's no obvious places inside that cable. Where maybe you ran it over with a chair and now it's cut inside. Maybe it didn't cut through but it's broken the wires, and such. Just look for damage to the cable. These are simple starting points that you want to check. If you realize, hey, maybe I did some moving. Maybe there is a physical problem. You might just want to go there first, but other than that, ipconfig, that's definitely where we're gonna start, because we got to see whether or not, we're even on a network and ipconfig and lets us do that. >> That's exactly it. So while we were getting that explanation, I went ahead and move about five or six computers and forgot to plug in their network adapters. Okay, just kidding. But we went ahead and set up a scenario, what would it look like if the media was disconnected inside a command prompt with ipconfig? Let's check that out here, so I'm gonna rerun the command. All right, and the very first thing you notice right here is media is disconnected, all right? So, first of all, I don't have an IP address, so then I can tell that's gotta be a problem here and I don't even see anything, I see no information. I don't see a MAC address or anything, so I can also check down here. My head's kind of covering it up, but down here at the bottom you got that little monitor icon, and notice, I gotta get my hand out of the way there. Notice how there's a little red x on it, that lets me know that the media's disconnected. And if I go into the Network and Sharing Center, I'm gonna go ahead and just re-enable this and then we'll get out of the GUI here and get back to the command prompt. All right, now notice the difference here once I rerun this command. Notice when I do an ipconfig, well, I get an IP address here. I get a subnet mask and I get my default gateway, and these are all important things. It is a necessity to have an IP address and the right subnet mask communicate on your local network, if you want to go across your network. Maybe for you home viewers out there, you want to go communicate out there across the Internet, then the default gateway is gonna be important, too. Some other information in here, as well, but this is definitely gonna be the start. Now, If you need to see additional information, right? More information than just what ipconfig gets, well we got a switch now, right? We add the switch with a /all. All right now, this is a ton of information guys, so you'll see a lot of IPV6 translational technologies. Now I see my Bluetooth adapter here. But notice that in the ethernet adapter area, notice that I get a lot of additional information that wasn't there before, right? I get information on, am I using DHCP, and if I follow this information over, right, I can see that, yeah, DHCP is enabled. So if for some reason I don't have an IP address, all right, well, I can probably say that it doesn't have to do with the fact that my computer's configured wrong. I might want to check out my home router or something, maybe that's being blocked, right, and we could even show you what that might look like, too. If I come in here and I do an ipconfig and I do a release, all right, basically what I'm telling this network adapter is I'm saying, I know the DHCP server's giving an IP address. I just want you to let it go, all right? Let it go, man. And we're gonna go ahead and run an /all here. And now you're gonna notice a little bit different here, right? Notice that DHCP is still enabled. Right, nothing has changed. I still have DHCP, but now I'm getting what is known as an APIPA address, right? Now an APIPA address, understand. And Dan made a good point as we were taking behind the scenes here that APIPA in and of itself isn't a tool, right? It's not a utility. But it could be indicative of a problem that you're having with your DHCP server, right? My computer now is calling out to the network and it's saying, hey DHCP server, are you out there? I could really use an IP address, right? Now, I kind of created this problem here, but this would look no different, right? So it's calling out and the DHCP server is snoozing. Well, that's a problem. Now what if I know that I've rebooted the DHCP server? I know it's online but I still don't have an IP address. Well, you seen the release, right? Sometimes you get a sticky lease where the computer just doesn't want to let it go, or you want to force the DHCP process to start over again. Well that's when we change that, and let me clear the screen and get towards the top so you guys can see that a little easier, now this is where I want to change that switch to renew, right? Now what's gonna happen? When I change it to renew, it's gonna take a second. Now you're gonna see something, an error out here, Bluetooth is not going to receive an IP address, and you should be able to see it. This operation can't be performed in the Bluetooth network connection. It's an expected error, right? We're not using DHCP on Bluetooth. But what I do see now is that I've got an IP address again, and if I get a little bit more information I can say that yes, again, DHCP is still enabled, right? Oops, there we go, DHCP is still enabled. I do have an IP address and now I also have what's known as an active lease. Kinda like a car rental agreement, right, or I'm gonna be in town for a while, I'm gonna be using this car, I've got the car for a week, same thing happens with your IP addresses. So Dan, ipconfig, ipconfig all, ipconfig release and renew All good switches inside of the IP Configuration utility, or IPConfig utility that can help you start on your network troubleshooting journey. >> Yeah, it's, like I say, it's a great place to begin, because you start getting an idea of the network connectivity that your device actually has. We saw it with Ethernet Zero. We looked at it. IPConfig's giving me an IP address Subnet mask. All the good stuff was there. Now, sometimes, you're setup for DHCP. You plug in, you turn on. Okay, my cables are good, but I still can't contact the network. Do an ipconfig. I have an IP address. I still can't do any kind of connectivity. The problem is it might just be set to at static address, That does happen, maybe someone came in and configured, maybe you did it during some testing. This happens. I've had it happen to me. You just forget that I had this thing set for a static address for whatever reason. Now I wanted to get a DHCP address, you gotta go back in, you gotta change that. Now that's not necessarily done through the command line... you can do it and we might even actually talk about that. But, using IP config is gonna let you know, I'm not on the correct network. I've got a static IP outside of the range of the network that I'm on right now. It's not valid. So, just using IP config is gonna allow you to see that and go, yes, I'm set for static. I'm need to change that to DHCP and now I should be good to go. So even though it's a very simple tool. Right? It just gives you output. You do have a few functional keys with it. It's got some switches you can throw at it and do some things. But normally, you're just using it for informational, or just hey, release that and renew me another one. Wes, is there anything else when it comes to IP config that we can learn about. >> There really is, and there are a ton of switches, like Dan says. There are a couple that I wanna point out, because we're gonna talk more about this troubleshooting, troubleshooting this service coming up as well. But DNS, DNS might be something that, you know, DNS Domain Name System, keep in mind it just takes our user friendly names and maps them to their IP addresses. So if we want to contact websites out there across the world, well Dan doesn't have to break out that old 50 pound book of all the IP addresses that he has written out, because you know we couldn't remember them all. Right, so DNS does name resolution for us. Well, you might say, well wait a second, Wes, I thought you just said IP configuration utility, right? Well what does that have to do with anything? Well, DNS has a lot to do with it, right? If I type a name in, I can't visit the website by its name, but I type in its IP address cuz I happen to know it, then I know there's a problem with DNS And that's where ipconfig display DNS. The display DNS switch can come in handy for us. So, if I need to for instance view the local resolver cache, let me show you what I mean here. I can do a ipconfig and I can do a /displaydns and when I do this I don't expect you to remember all this information. Dan, did you catch that last one? >> Every last bit. >> All right, I got that. [LAUGH] And this is a good thing, right? So this is the local resolver cache. And what does helps you do? It helps speed up the response times between the time you type in that name to actually connecting to the web page and it being delivered right. It's like caching area if you will. Why send a communication out to your ISP's DNS server and wait for it, even though is milliseconds, wait for it to come back if I can look locally. I know where the IP address is based on it's name because I have it right here on this machine. Now doesn't necessarily happen a lot but it could on your internal network especially if you're maintaining your own internal DNS server and there's some changes like internally and inside of your infrastructure. Maybe you've got a intranet site that your company, you go to and you visit employee documents and stuff like that. And for whatever reason, it doesn't happen a lot, but for whatever reason maybe the IP address changes. Well if you haven't turned your computer off that IP address could be in one of these records, right? And it could be mapping you to your internal company website to an IP address that no longer exists, or isn't relevant right now. Maybe it changed. The problem is because this caching system is the first place you're gonna look I'm never gonna send a request, hey DNS server, where is www.employeehandbook.com. Let's say that's our intranet site. Why? Because I've already got my answer locally. Right or wrong, I've got my answer locally and that's what I'm sticking with. So that's where the next one comes in. I might wanna do something like this. I might wanna do, instead of a display DNS they call that caching a stale record, right? It's stale because it It no longer maps to a valid IP address. So instead what I could do is a flushdns. All right now this works as well. But you know, we're in the command prompt you can also do this in PowerShell as well. So you pay attention to some of the PowerShell episodes we got out there. Cuz likewise you can do a get-DNS client cache or a clear-DNS client cache. But we'll stick with the command prompt here and we'll do the flush DNS, ipconfig /flushdns. Now Dan, did you catch that one? That one wasn't too bad, right? We didn't have a whole bunch of records going through. >> A big flyby. >> That's right. So let's go ahead and display our DNS cache again. And notice it says, could not display the DNS Resolver Cache. So, if I do feel like that name resolution is an issue because of a stale record, right, well, I can flush that. You say, well how did you get to that point? Well, let me show you, all right? If I go back to my ipconfig /all, notice that I am using a couple of DNS servers here. Now, Dan, I'm sure you could pick up on what these servers are, right? >> If they are the 8.8.8s, then, yes, they are, I believe, Google's DNS servers? >> That's right. Yes, sir. Very good. Very good. And for the most part, guys, I really have never had these not return a response on me. And I'm sure they're using some kind of load balancing in the background that we're not aware of. But they usually give responses, so I know, all right, that I've got at least a DNS server set up, all right. So I could say that maybe that the DNS problem that I was having was directly related right there to these records. Now you say, well wait a sec, are you browsing to anything in the background? Well Yes I am. Alright, you guys could probably see that I got my Chrome browser opened in the background. Well it's doing a keep alive, right, with Google server. So it's still resolving names because I've got that active connection. So it's constantly generating those records and again real fast. If I wanna clear them, there you go. It's, they're all gone It's gonna make me close that down, isn't it? There we go. And let me clear the screen up here one more time and we'll display the DNS. So very easy way that if you do think related to IP config that you're having some kind of DNS name resolution issue, just go ahead and flush the cache. >> That's right. Now the one two punch as we like to call it here Is usually, you start with IP config and you say, okay I see that I'm on a network. Now it's time to start testing connectivity. Do I have connectivity with a certain device? This is a very common troubleshooting technique that we use. And the utility that we use in that one-two punch is gonna be your good old friend ping, right? >> That's right. >> And I know everybody, I learned it as the Packet Internet Groper. From what I actually understand, that's actually kinda anachronistic. It came later to be called Packet Internet The original developer just meant it as ping, like sonar. I'm sending out a noise and I'm waiting to hear back from it to measure whether or not was something there, and that's the idea, right? >> Nothing like retro naming to confuse you. That's exactly it. We've got to use ping. All right, now ping It sends out little signals. These little signals that go to whatever device it is that you're testing them and they say, hey, are you there? And we should get some replies back. Now if we get replies back then we know from the standpoint of this device here and whatever device I sent that information to That we can communicate. But there is a process to do this. Let me give you the real world scenario. If I'm testing internet connectivity, I'm going to test against the Internet, right? But there is a right way to use ping. You start as local to your computer as you can, and then you slowly work your way to your perimeter of your network, and then, finally, past your network. And that is a good way. Like I said, for those of you that are watching that have used ping before, and I'm sure we've got some of you out there, say, well, why don't you just ping the Internet, or something out there on the Internet, and find out? Yeah, well, that's good. But if you had a multi-routed environment internally on your network, that's not always the case. First place that we're gonna go, we say there's no place like home, right? So first thing I'm gonna do is, I wanna test my operating system's ability to speak the language of the network. In this case, the protocol being TCP/IP. So the first thing I'm doing is I'm pinging the loopback address, and by default we usually say 127.0.0.1. Now this doesn't send any electrical communications out of the network adapter. All this does is says, internally, does my operating system understand the DNA that we're using, or the communication protocols that we're using for this network. And at this point I'm getting a reply back. I can see that the operating system knows what's going on with the TCP/IP. Now what if I want to find out does my network adapter have the ability to respond to itself when its called on? Dan says we have our piece of information, however it might be. A share or something like that. Well, Dan, I didn't know that my network adapter can respond to that request. So here's what we do. Next thing that we're gonna do is we're going to ping. Oops. I'm gonna spell that right. We're going to ping our own IP address. Now, you know what's kind of funny? I think I've forgotten my IP address after all this looking at it. So that's why we got ipconfig, and that's why Dan said a one-two punch. First of all, I've got to find some IP addresses that are valid and relevant to me personally here. I can see my IP address there is 10.1.230.54, and if I do a ping. What was it? 10.1.230.54, I see that it returns a response. And if I want to, I'm gonna make that persistent here, as we go. If you're in the other operating systems it's persistent by default. Windows it isn't. But, what I'm doing here is my network adapter is being called upon. Now it's being called upon by the operating system, and it proves to me that my network adapter, when it's called on, it can say, yeah, I'm over here. You can talk to me. So that we can see that we are getting responses from the network adapter. However, we do have to go a little bit farther than that. From the standpoint of this computer, I know that this computer can communicate with the network. Now that doesn't mean that this computer can communicate with any other device on the network, which is our next step, right? Now we're as close as we can, the operating system, the network adapter that is attached to the operating system, or the other way around if you will, and then, finally, another computer on my network. Well, there's a couple of that things you can do. If you end up having like, maybe a separate DNS server on the internal network, just do an IP config, or find that DHCP, or DNS server, and ping it. A lot of times I will tell you that our default gateways for doing all of that for us. So that might not be an accurate test. So what I've got is another machine, out here on the network. Well, first you have to use an IP address and you have to use the- >> Valid notation? >> Make sure you use ping, right? >> [LAUGH] >> That's what we're talking about here. >> It just knows inherently, you wanna use ping. [LAUGH] >> Yeah, that's right. That's right, and you know I might not, one of the things, let me see here. It might have gone to sleep here. Make sure I got that right. And you know what? It doesn't look like it's pinging. So the good thing about this is, I've communicated with other computers on this network. So this is one that we weren't really going to talk about here, but I'm going to go ahead and throw it in here anyways. ARP is the Address Resolution Protocol, and if my computer has talked to other computers within the network, it should have cached their MAC addresses and IPs. So I want to see if I've got another computer in here that maybe this one, looks like we've got a few here. All right, so I'm gonna try one of these other computers that are on the network. Apparently at one point, I was communicating with them. So I can use this database as a way, really, to find an IP address of another computer on my network. So a kinda little cool thing, even though we weren't really talking about ARP there, that we can throw in. >> The only caveat to this is these are computers that Wes already knows that they're alive. He's already made a connection to and is talking to. If you're trying to trouble shoot a computer that you don't have that knowledge, the computer has never spoken to it, well, at least since it's been up and running, then you're not going to be able to use ARP to make this happen. So you might just have to go the old sneakernet way. >> That's right. >> Run over there, check that computer, find out what its IP address is, use good old ipconfig, >> Yeah, that's right. >> and then do that. If you have a user on the phone, if that's the scenario, you can just say, hey, do me a favor. Show them how to open a command prompt. Type in ipconfig. Tell me what your IPv4 address is for your computer. And now you'll be able to do that. Otherwise, we can do this. This is for demonstration purposes. >> Yeah, definitely, and thank you for that, for sure. So now we've got one of the IP addresses, and I just picked one out of the list here, and we'll see if it is good and going. So, we can see that we can ping it. It is there. Like Dan said, I've got another computer over here that it is connected to the network, and I might just be doing exactly that, sneakernet. I'll go over here, do my ipconfig on this computer that's off to the side you guys can't see right here, find out its IP address, and try to send a ping to it. Now let me tell you something a little bit about the ping. We're gonna stop right here, just for a second, because ICMP can be a security risk, all right? So we've got to understand that. Let's take right here for ITProTV. There might be something set up, maybe Don or one of other hosts here, he might have something set up that he doesn't want anybody just pinging and sending all kinds of data to. So for security purposes, they might block that. So ping isn't a one-stop-shop. If you ping one address and it doesn't return replies, try to ping another one, just to make sure that IMCP isn't being blocked. Now, what have we done, Dan? So far, we've got our operating system is good. >> Mm-hm. >> Our network adapter is communicating, it's responding. Now we've got another computer that's responding. So at this point, internally, locally in my network, I know from the standpoint of this computer I can communicate. But let's go a step farther. We're going to the edge of the network. As far to the edge of the network as we can get is the gateway. They call it the gateway for a reason, right? So the last thing that we're gonna do, well, second to last thing that >> Second to last. >> we're gonna do. That's right, can't forget the last one. The second to last thing that we're gonna do is we're gonna ping our default gateway. Now, you might be asking yourself, well, what if I don't know the IP address of my default gateway? Yes, you do. Let's go back and show you. You remember, we've been using the ipconfig? Kinda see that one-two that he's talking about, why it keeps coming up back and forth? We use them a lot, they go hand-in-hand. And notice that I got my default gateway here. All I have to do, and let me put this up to the top so you guys can see that. We'll do a ping. We'll do a 10.1.230.1, all right, and then I'm just making these persistent. Guys, you don't have to use the switch tee. I'm just used to some of the other operating systems. You know, ping doesn't shut off until you tell it too. >> You know you bring up a really good point. It is a good practice to start using the persistence. I do it all the time because maybe I'm getting intermittent connectivity, and I can see you when the pings dropped out. Maybe there's a pattern to it? Maybe I see it goes from five minutes, and then it drops. I lose all my pings. They go away. I start getting request denied, or unavailable, or whatever. I can't get to it. Now they're back up, five minutes later, I'm starting to see a pattern. I can say, well, there's something going on in this network between these two devices. Sometimes it's a flapping port on a switch. That can definitely cause things of intermittent connectivity. That is a great way, and using just ping will help you figure that out. Maybe I'm installing a new piece of network gear? I've bought a new switch to replace the one that's got flapping ports. I'm like, okay, throw that in there. I can do a persistent ping, put in my new switch, run all the configuration, and when those pings come back alive, I know that that switch is active. Everything is now working, and using ping to do that. Very simple tool, but I know guys that are like CCIE level and that's what they use to check connectivity with because it's a simple tool, it's easy to use. >> It really is, now I wouldn't recommend doing this from a remote location. And Dan's got plenty of stories of why you don't reboot servers from a remote location. Now if I'm on location, right, and we're gonna walk right over to, for instance, our server closet here at ITProTV, right. I will use a ping to do a reboot on a server, right. I'll issue the ping, and then I'll make sure it's active. I'll reboot the server and I don't really have any way of telling very early on if that server has been rebooted. And just like Dan says, it goes intermittent, and then when it starts receiving replies back I could fire up Remote Desktop, I'm back into the server before you know it. But, I would never recommend doing that on a remote location, because if the server doesn't come back online, you're in for a drive. All right so, very easy utility to use here Dan, and I'm just doing a Ctrl+C guys by the way, that'll stop it. Ping, very, very good utility. Now, we ping the default gateway, we see that up until this point, at the edge of our router, we can communicate. But now we've gotta go a little bit farther and you might hear some people say, ping a remote network. Well, in TCP/IP speak, that just means any other network to the one that your computer's on. It just so happens that if you're in a home environment and watching this, a lot of times it's the Internet. So one of the last ones that I do is ping a location out there on the Internet. And there is plenty of them, in fact we've already mentioned one of them that I use to see if I could replies back. And that's Google's DNS servers out there, right? They're pretty good, I mean DNS, you want it to be online or the backbone of the Internet goes down, so they want those servers to be online. Let me show you what I mean. All right so we'll do a ping, 22.214.171.124. And when we run that, oops, we'll run it right off the screen and out the front door and out of the office. So we can see that we've got some replies back now. And from the standpoint of this computer, it knows TCP/IP, my adapter's fine, I can communicate with other devices. My gateway, I can get to the gateway, and now I can even route traffic off of the gateway. >> That's right. Now it comes to the part, well, we've gotten ping, right? It's underneath our pelt, it's in our toolkit, we can use it effectively, and I want to ping something. I'm trying to test connectivity with something that's outside of my network like we did with those Google DNS servers. What happens if I ping them and they don't reply? It could be one of two things. And well, first thing is they should be blocking ping, right? That could be the thing of it. And if it is, well, let's try something else that's not blocking ping. Continue to work through things that are outside of your network until you find one that replies. That way you know, maybe you know something specific that's out there that allows for ping. You can use that, write that down, keep that in your little toolkit. If I need to test outside connectivity with ping, I can always go to this because it's not blocking ping. But what if I'm still not getting it and I know it's not blocking. That leads us to our next tool right? >> That's right, and that's called tracert. Now those of you that maybe have seen this in other operating systems, they spell it out. Sometimes even in the Windows world we'll say traceroute, technically it's not accurate. It's tracert, traceroute is in the nix-based systems. However, as far as functionality goes they're very, very close to what they do. Tracert here in Windows and traceroute out there in the nix system, traces the path a packet takes from source to destination. So we typically have more than one hop across remote networks and especially in packet switch networks, we usually have more than one hop. Well I need to know where the communication breakdown is happening. So imagine a utility that lets me roadmap, right, like a footprint, like cookie crumbs, right, footprint on the sand. And I can see which path it's taken when leaves my computer and goes to that destination. I wanna track each hop, right, the hop is the act or technique of forwarding traffic between two routers. Let's see what that does for us, right? So if I do a tracert, and I tell you what, first of all, you can do this a couple of ways. Keep in mind that if you use a name, you better hope you tested your name resolution to use that first, right? Because it's still gonna be use a name resolution on the background. If I do www.google.com, right, so that's a name. And if I run the tracert on it, you can see that it's resolved the name here at top. Notice that it gives me an IP address and it says tracing route to www.google.com. And then it gives me Google's IP address. And you see some of this information coming out, we'll see here in a second. If you do a tracert that way, it's contingent on having name resolution. So if this fails, don't just automatically assume that the route itself has failed. It might be name resolution and DNS is snoozing, or whatever is going on. You might have to do some of those DNS troubleshooting that we were talking about. And let me show you what I mean, so I'll tell you what, I'll give that demonstration in a second. Let’s see what we're looking at here, Dan. All right, now I've got a series of hops, right, it says 9 hops. It'll trace it over maximum of 30 hops, you'll see. That means that's the maximum information it's gonna give back. All right, now I can see the first hop. You say, well how is this information useful to you? Well here in Gainesville, this is actually really useful information. And Dan, as you know, our major provider here locally, our local ISP is gonna be Gainesville Regional Utilities. Right, well call them GRUCom here, it's just shortened for Gainesville Regional Utilities. Well I can see that I'm on their networks right here. In fact, you can see I go all the way out to their networks. I wanna say this is somewhere in the Midwest I believe, but anyways it's on their local ISP. So if I start to see things like timeouts, right, you might not see any information, right? If I start seeing this request timed out, request timed out and it's on this local network, couple things could be happening. It could be a firewall, right, again, this is based off a ICMP just like ping is, so they might not want you having that information. So it might give you these little asterisk symbols here. However, what I can see is that, if I start getting latency, right, these milliseconds here, maybe it's not going past this location. It gets to maybe this fourth hop here which, again, is still GRUCom's network, and it stops. I'm getting request timed out. Well, since it's my local ISP, I can call them and say hey, what's going on? Is there a problem with your network right now? Because I'm seeing I can make it to your network, but my data can't leave your network. And somewhere in the mix that somethings happening, they'll probably tell you no, it's not their fault. You need to turn your firewall of or something. No, just kidding, don't ever do that. [LAUGH] But what is also interesting here too, and this is what I always think is just the information that you, oops, as I click all around the place there, is this last one, right. This last one's kinda cool, right. This is one of the IBPs, the Internet backbone providers, right. So the top dogs, if you will, in the Internet hierarchy. There's nine of them globally and we can see that this is Level3, one of them. Now, if there's a problem right here, there's absolutely nothing you can do about it. Cuz these guys have the best network engineers in the world. They're trained to just deal with stuff in seconds. But you can get a lot of good information here, right? I can find out things latency. Right, when it comes to the latency, from here to there, round trip times. If I start seeing some high latencies here, I can say okay, that's why performance is maybe not so great. It goes to my local ISP, my local ISP, in this case GRUCom, they're doing great. It gets out there, hits another network, and all of a sudden I start seeing these milliseconds jacked up through the roof. I know that they're having latency off of somewhere out there across the Internet. And unfortunately, there's nothing I can do. But it is good to know where that packet's going from source to destination if png should fail you. >> That's right, Wes has laid this out exactly what you wanna know, right? We have all the different hops that my packets are taking to get to their destination. If you ultimately get to trace complete, well, you're getting to where you're wanting to go. You might have some of those failures like Wes showed you. But it just means they're probably not replying to that information. It's saying stand off, usually a firewall, maybe it just doesn't have that feature turned on, and that's what's happening. But as long as you get to the end of it, you should be good to go, you have connectivity. But if you're not having connectivity, you never get trace complete and it stops, and it stops, and it stops and it never keeps going, well at least you know where the problem is. You go to your provider if that's were it might be. If it's outside your provider's network, maybe the information is in there where it's stopped and you can call them and say, are you having a problem with outage? People dig through optic cables all the time. And I've seen the whole state, sides, and the entire state of Florida go down before because entire providers are done. Something happened with their fiber backbone and that's the end of it. And you'll see that when you start the traceroute. You're saying, okay well I can get to my network, I can even get outside ov my network a certain bit. But where am I stopping? It's with my provider, let me call them. Are you having any issues? They'll verify, yep, we had a guy, didn't call before he dug, and sliced right through our fiber backbone and we're having issues. At that point, it is, it's out of your hands, there's nothing you can do but wait. You got an SLA with your provider, they're gonna give you some sort of compensation for that, sometimes, as long it's outside of the realms of what they expect to see. But then there's nothing you can really do, wait until that connectivity comes back. Now Wes, we've got a few more tools that we wanna go through, but that clock is well done. We went well past it. So it looks like we're gonna have to have a part two on network troubleshooting with command line tools. >> That sounds good, it looks like we killed the clock. >> Yeah we sure did. >> [LAUGH] >> Look forward to seeing you there. >> Definitely. >> Thanks for stopping by. Thank you guys for watching. Hopefully we'll see you in part two. We're gonna go ahead and sign off for ITProTV. I've been your host, Daniel Lowrie. >> And I'm Wes Bryan. >> We'll see you next time. [SOUND]