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Hey everyone and welcome back. Now previously throughout this skill we have been primarily

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focused on DHCP from the point of view of assigning addresses from a particular range.

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That is if someone happens to request an IP address they get it from that range but it

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could be anyone from within that range. No one is guaranteed a particular IP address.

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Now I did hint at the start of this skill with respect to things like servers on a network

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or maybe things like printers. These external devices which are used by other clients within

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the network very often we want to have some type of predictability about these IP addresses.

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So in this case it does actually make sense that we do have some type of static configuration

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such that when these devices come back online they just reach out with a broadcast address

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and they can get the same IP address no problem at all. So let's dive in and see how we can

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actually do this configuration directly within our DHCP.configuration file. So what we'll do

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here is we will go directly back to that file and I will say sudo nano xa dhcp dhcpd.conf

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and in we go. Okay so let's scroll on down then. So under our subnets what I'm going to do here is

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not use the subnet keyword I'm going to use the host keyword so I'll say host and now I'm going to

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give this host a particular name. So let's just imagine that my other Ubuntu machine was acting

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as a web server as well okay. I'll just say web server and now what I will do is I will open my

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curly brace and then what I'm going to say here is I'm going to say the word hardware and now I'm

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going to specify the actual layer 2 MAC address for that particular device because you may recall

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the layer 2 address is a physical address that is actually on the network interface card for that

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device whereas an IP address is a logical address which is assigned and not particular to the machine.

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So if we go back to this machine that we want to give a static IP address to so I can say IP link

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to show all my layer 2 information. So let's say we wanted to give this interface here the same IP

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address what we would do would take note of its MAC address which is this right here meaning that if

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we get a broadcast from this interface the DHCP server will note the MAC address here

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and it's going to give it the exact same IP address every single time. So let's try that out then.

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So I'm going to say hardware ethernet and now what I'm going to do is to specify that MAC address

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I just saw there so that will be 80 colon 00 colon 27 colon D0 colon FE colon E2. So what we're saying

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here is if we get a request from an interface which has this particular MAC address we're going

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to give that interface a fixed address okay so remember this keyword here and now we specify

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what is the fixed IP address so we could just maybe say 172 16 1 dot I don't know 4 let's just

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say whatever it may be and I will do my semicolon and then my curly brace so there we have it.

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So that would mean if that computer went offline and it suddenly came back online and it sent a DHCP

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discover request from that interface we would match on its MAC address and send this particular IP

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address now we could shut the machine off we could restart it multiple multiple times every

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single time that machine comes back online that interface is going to get this IP address so really

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once we've done that we can just save our configuration and all we would have to do would be to restart

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our server so those systems CTL restart isc DHCP server and to enter and those new configurations

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would take place so now one final thing which I just want to briefly draw your attention to that

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you should be aware of for the purposes of the examination is that with respect to our DHCP

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configurations much of what is going on is going to be logged now we have to know the location of

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where we can find our logging messages now this will vary depending on the system you happen to be on

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if you happen to be on a red hat based system this is going to be found very likely within the var

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directory and then within the log sub directory and then within here we should have a file called

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messages inside here you should find all that type of you know that Dora discover offer request

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acknowledge as well as a whole bunch of other DHCP related information however if you happen to be on

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an Ubuntu based machine that would be in the var directory within the log directory and it should

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actually be in something called daemon dot log for Ubuntu machines this should actually be where

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you find those DHCP log messages and that really is all we have to do with respect to our static

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host configuration via DHCP we take a note of the hardware address and then we specify that fixed

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address that we want to bind to that hardware address and suddenly those DHCP offer from the

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server are going to be very consistent offering out the same IP address to the same interface very

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very handy like I say when dealing with servers and printers in particular okay doc so I hope

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this has been informative for you and I'd like to thank you for viewing