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So in our journey, we've done iCMP jitter, UDP jitter, we've done HTTP SLAs. In

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this video,

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I'd like to walk you through setting up an IPSLA measuring DNS. So if you want

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to verify that

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the DNS server is functioning correctly, we can set up an IPSLA to test that.

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So for our test,

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we'll use R1 again as the probing device, we'll use server 1NUG as the DNS

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server,

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and for the DNS request we want to make it from that server, I know on that

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server I've got an entry

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for PC1. So we can do a query for PC1.nuggetlab.com. And if we get a response
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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for PC1. So we can do a query for PC1.nuggetlab.com. And if we get a response

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back, it is successful

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for that name and it resolves it correctly, that would indicate that our IPSLA

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is okay. And if we

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don't get a response back from that for any reason, that would cause our IPSLA

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to fail, meaning

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giving us a negative result indicating it's not working as expected. So let's

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head over to R1

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and set up this new IPSLA. And for the IPSLA number, for jitter, we did one,

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and this is two,

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and this is three, so let's go ahead and use the IPSLA for DNS, and let's use
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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and this is three, so let's go ahead and use the IPSLA for DNS, and let's use

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IPSLA ID number four.

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So here back at R1, we'll do a show IPSLA summary to remind ourselves where we

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're at. So we have

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three SLAs, they're all currently at this moment, they're all still running. So

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let's go to configuration

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mode, IPSLA, for press enter. And for this one, we want to do DNS. So we'll go

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ahead and type in

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DNS, or copy paste it in space question mark. And the DNS name we want to

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resolve is going to be

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PC dash one.nuggetlab.com space question mark. And then we're going to type in

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name server and
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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name server and

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specify our name server, which is down at 192.168.1. This is verified to dress

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real quick in the topology.

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That's at 192.168.1.100. We'll put that in as the DNS servers IP address. And

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for the source IP

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address, we don't have to specify a source IP address, but it'll be easier to

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pick up out of the

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packet capture, because other devices may be making DNS requests. So specify

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also the source IP,

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and we'll specify the source IP address as the loopback on our one. So type in

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source dash IP,

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and the loopback address of 1.1.1.1. And that's it and press enter. And then
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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and the loopback address of 1.1.1.1. And that's it and press enter. And then

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for the frequency,

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let's go ahead and do that every 30 seconds. And we'll type in exit, so do show

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run pipe

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section SLA. So we can see our work, and take a look at IPSLA for which is

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right here. That looks

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good. However, we do a do show IP SLA summary. It is not running. And that's

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because we need to

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start it. So as we did previously, we'll go ahead and start it, except the time

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we'll specify

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the SLA idea of number four, I'm going to start it now and just tell it to run
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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the SLA idea of number four, I'm going to start it now and just tell it to run

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forever and press

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enter. And now it should be running. So we'll do do show IP SLA summary. And it

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is. All right.

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So it's running, it says it's okay as far as the return code. And if we did a

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command show IP SLA

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statistics, and then we put the SLA number for that DNS SLA in, which is four,

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and followed by the

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keyword details and press enter, it gives the details on that. So number of

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successes one,

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which is great. And it'll continue to grow as it does probes, in our case,
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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which is great. And it'll continue to grow as it does probes, in our case,

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every 30 seconds. So

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if we wait a few seconds here and the same command again, now we have number of

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successes too.

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Fantastic. And if you want to see what that look like on the back end with a

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protocol analyzer,

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let's take a peek at that as well. So we'll start our capture here. There's a

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lot of DNS

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happening. However, I think a lot of that is coming from our Windows client.

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And oh, here's one from 10

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dot 0 dot 12 dot one. I saw that there so I wouldn't stop that. And let's go

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grab that one. So 10

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dot 0 dot 12 dot one. Oh, that's OSPF. So let's go ahead and do a display

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filter. And let's just
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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000

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filter. And let's just

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look for DNS. So put that in as display filter. And then here is an example

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right there packet 31,

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they open it up, make that a little bit bigger and scooch that down just a

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little bit. So there's

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our DNS request that our one was making. Here's the query looking for PC one

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dot nuggetlab.com.

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It says the response is in packet 32, which is the following packet. So we'll

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go ahead and close

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that. And let's take a look at packet 32, the response. So make that a little

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bit bigger. So

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here is the query. And here is the answer. If we expand that and the response,
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here is the query. And here is the answer. If we expand that and the response,

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the DNS answer

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to that, what is the IP address of PC one dot nuggetlab.com. It shows it as 10

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dot 0 dot 1 dot 10,

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which if we look at our topology happens, good news happens to be correct. That

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is PC one's correct

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address. So that's an example of our probe going from our one down to our DNS

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server,

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just to validate that service is up and running and functional. So if we go

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back to our one,

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and we do a show IP SLA statistics for details. Now it's had seven successes.
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and we do a show IP SLA statistics for details. Now it's had seven successes.

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And there's the

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latest round trip time is 72 milliseconds. So another critical service that we

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can measure with an

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IPS, like would be other things like FTP services or DHCP. In fact, in the next

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video,

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let's do an example of testing and validating their DHCP services are working

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and measure that

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by setting up an IPS a looking for DHCP. So I'll see you in the next video for

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exactly that.