welcome back in this lecture we will be looking at the address resolution with respect to ipv4 and ipv6 this is the module 9 of the cisco netacad introduction to networks lecture series if you would like to watch the previous lectures i will leave a link in the description with the lecture playlist so that you can go ahead and watch them in this lecture we will explain how app and nd enable communication on a network we will look at the mac and ip up with respect to the ipv4 for example and the neighbor discovery or nd with respect to ib ipv6 mac and ip there are two primary addresses assigned to a device on an ethernet lan the layer 2 physical address which is the mac address and the layer 3 logical address which is the ip address the layer 2 mac address used for network interface card to network interface card communications on the same ethernet network while the layer 3 logical address which is the ip address is used to send packet from the source device to a destination device the layer 2 addresses are used to deliver frames from one network to another network that's a very important concept that you learned pre on our previous modules and if the destination ip address is on the same network the destination mac address will be that of the destination device so this particular slide basically showing that what we already learned and it's just quickly describing what it is it's just a quick summary of what we have covered in our previous modules again if you would like to watch the previous module lectures you can go ahead and check my youtube channel and you'll get to those lectures and you can watch them so you should already have an idea about the difference between a mac address and ip address so remember mac addresses are used for communication between network to an interface cartoon network interface card within the same ethernet network while the ip addresses can be used to communicate across multiple networks destination on remote network when the destination ip address is on a remote network the destination mac address is that of the default gateway up is used by ipv4 to associate the ipv4 address of the device with the mac address of the device network interface card while the icmp version 6 or v6 is used by the ipv6 to associate the ipv6 address of the device with the mac address of the device network interface card so remember in ipv4 the process is the app that is used for the association of mac address to the network interface card while in ipv6 the ips ic mpv6 is the process that it will be used to associate the mac address to the network interface card if you have access to the netacad please go ahead and do your packet tracer lab with associated with this particular module and i will be posting these packet tracer labs on my youtube channel in the future so it's not going to be part of this lecture video so i'm just going to skip through this slide but if you have access to the cisco netacad you should stop right now and then just go ahead and do this packet tracer a lab which which is title identify mac and ip addresses up a device uses app to determine the destination mac address of a local device when it is known its of ipv4 address app provides two basic functions resolving ipv4 addresses to a mac address and maintaining an up table of a ipv firm to mac address by simply mapping them so so again i provide two basic functions resolving ipv4 addresses to a mac address and maintaining an app table of ipv4 to mac address in the device to send a frame a device will search its app table for a destination ipv4 address and a corresponding mac address so just like a uh you know like a cam table uh the the we will have an app table that will have the destination ipv4 address and the mac address associated with that ipv4 address or very sp the specific ipv4 addresses and the mac addresses associated with those specific devices if the packet's destination ipv v4 address is on that same network the device will search the app table for the destination ipv4 address if the destination ipv4 address is on a different network the device will search the app table for the ipv4 address of the default gateway this is very important concept that you should learn if the destination ipv4 address is found on the uh on the up table and it is on the same network the device will search the app table for the destination ipv4 address but if the destination ipv4 address is on a different network it the device will search the app table for the ipv4 address of the default gateway so that's an important concept that you understand and if the device locates the ipv4 address its corresponding mac address is used as the destination mac address in the frame and if there is no up table entry found then the device sends an up request so that it can update that up mac address ip address mac address relationship so remember that if there is no up table entry found then the device sends an up request and that request is used to update them up table so they can associate that ip address with the the the device mac address there's a video that explains this much better uh using a demonstration and this video is available to you on your cisco netacad website if you don't have access to cisco netacad i will post a link in the description uh for a copy of that video it's called the up request you should go ahead and check it out and that will explain this much better uh so yeah that's what this slide about and the next slide uh there's another video about app operation um it's called up operation uh up reply uh and again if you have access to cisco net account you can go ahead and watch them oh i will leave a link below in the description and you should watch that video as well and even in the next slide we're gonna have the up role in remote communications video it's again a demo created by cisco netacad people and i have a copy of that available on my youtube channel i will leave a link below if you do not have access to your netacad account netacad course material you'll be able to watch that and i will leave also a card on our uh on this video or it's on the top right hand corner uh you can click on the cards and you will see the list of these so all of these these three videos uh it should appear on the top right hand corner cards of this youtube video and you should be able to click on those and watch those removing entries from an up table entries in the up table are not permanent and are removed when an up table cache timer expires after a specific period of time so remember how the up table get updated with the specific ip address and association associated mac address and it use this that up request to get that information so that the table get updated well when the there is a timer that so that those entries get cleared once uh it's not being used for a while so the destination of the up cache timer differs depending on the operating system so cisco devices may have a certain up table configuration compared to a windows device and some other device etc etc up table entries can also be removed manually by the administrator by sending a command to the router or the switch or the you know the end device what you need to remember is the app entries are not permanent and are removed from the cache after a specified period of time or sometimes when the device gets rebooted up tables on networking devices so on cisco networking devices especially on routers you can type the command show ip up so show iparp command and that will display the app table for that cisco device and this is an example of a cisco router that displaying that information with the show ip up command on windows computers such as windows 10 and windows 11 pcs you can open the command prompt and then on command prompt you can type up dash a so up space dashing and that will display uh your app information the app table on your windows pc and then you can use that for your network administration purposes up issues up broadcasting and up spoofing up requests are received and processed by every device on the local network excessive our broadcast can cause some reduction in performance such as it could actually create less things like network congestion for example up replies can be spoofed by a threat actor to perform an arm poisoning attack enterprise level switches include mitigation techniques to protect up attacks so i will not go into detail and depth of up attacks and how sso our broadcast could create network conjection in this lecture i will post a separate video explaining different network attacks and how you can mitigate them but for this course what you need to remember for this module is that there are vulnerabilities with up uh they include a broadcast which could create network conjection and the other one would be the uh up spoofing by a threat actor that could cause a up poisoning attack and in terms of detail on how they work i will go over that in a different video for now just remember that our broadcasting and up spoofing is a have some vulnerability issues um in our network systems again if you have access to your cisco netacad there is a packet tracer lab that you should be doing i would pause this video go ahead and do that lab and then come back and watch the rest and again i will make sure to post those cisco netacad labs on my youtube channel later this week ipv6 and never discovery again there is a video made by cisco netacad called ipv6 neighbor discovery that video will explain the process of how ipv6 perform address resolution using icmp v6 neighbor solicitation and neighbor advertisement messages and i will leave a link in the description of this video in case you do not have access to cisco netacad material and you can also click on the cards at the top right hand corner where you can click on that video and watch it ipv6 never discovery messages the ipv6 neighbor discovery or nd protocols provide address resolution router discovery and redirection services icmp v6 neighbor solicitation ns and neighbor advertisement name messages are used for device to device messaging such as address resolution icmp v6 router solicitation rs and router addressment array messages are used for messaging between devices and routers for router discovery icmp v6 direct messages you see used by routers for better next hop rest selection each one of these items i will go in detail later but for now for this course this particular modules what you need to remember is that the neighbor discovery nd protocol provides these items like address resolution router discovery and redirection and the ns na rs array uh you know what they are what why they we use them use and use it and what what these items are responsible for in the ipv6 neighbor discovery messages ipv6 neighbor discovery address resolution ipv6 devices usually uses nedba discovery to resolve the mac address of a known ipv6 address icmp version 6 neighbor solicitation messages are sent using special ethernet and ipv6 multicast addresses so that's how it actually communicate between ipv6 addresses so we have ic mp v6 neighbor solicitation message it would be something like you know just like saying hey who whoever has this particular ipv6 address please send me your mac address so it's like a app message but for ipv6 and then when that message was received by this particular ip address in this case in the pc2 it gonna reply back saying hi i am that ip address and my mac address is so so on and so forth and then that information get updated uh when the message been received back uh from that advertisement message so we have a icmpv6 solicitation message saying hey i need that who who has this ip address please give me that mac address belong to that ip address and then the person the device that has that ip address gonna give the icmp v6 neighbor advertisement message and that will give that you know connect that ip address to that mac address so that's how it works again this is just briefly going over how ipv6 work and i will go into depth of exactly how ipv6 neighbor solicitation and neighbor discovery and all of these things work on a later video but just for now just remember this is how ipv6 differ from ipv4 up messages there is a packet tracer lab activity on your cisco netacad and if you have an access to your cisco labs go ahead you should be doing that right now again i will post those labs on my youtube channel later sometime this week or upcoming weeks and this is the end of this lecture and i will quickly go over what we learned in this lecture we learned that the layer 2 physical addresses such as ethernet mac addresses are used to deliver the data link frame with the encapsulated ip packet from one network card to the next network card but however these physical two net addresses are being used uh to communicate between network card to network card on the same network if the destination ip is on the same network the destination mac address will be that of the destination device when the destination ip address whether it's ipv4 or ipv6 it doesn't really matter is on a remote network the destination mac address will be the address of the host default gateway for example in your house the your default gateway going to be your router's interface an ipv4 device uses app to determine the destination mac address of a local device when it knows the ipv4 address app provides two basic functions they are resolving ipv4 addresses to a mac address and maintaining a table of ipv4 to mac address mapping which is we call the app table after the app reply is received the device will add the ipv4 address and the corresponding mac address to its app table hence updating that markup table for each device and up cache timer removes up entries that have not been used for a specific period of time and that timer changes based on the device that you are using such as cisco devices versus dealing devices versus your windows device so it's a random timer ipv6 does not use up instead it use something called net neighbor discovery protocol to resolve mac addresses an ipv6 device uses icmp version 6 neighbor discovery to determine the destination mac address of a local device when it knows its ipv6 address so if if you have any doubts uh about this lecture anything that we discuss in this lecture you can post this uh video right here and this is a really good summary of what you should have learned uh for your quizzes and exam in this particular module and that is the end of this lecture if you have any questions or concerns related to any of the topics that we covered today you are feel free to leave a message in the comments and i will make sure to get back to you if you would like to watch the previous videos as i mentioned before i will leave a link in the description uh for the playlist of cisco netacad introduction to networks like lecture series please make sure to thumbs up this video as well as subscribe to my channel so that you would not miss my future uh lectures on cisco netacad related materials as well as other technical materials that i'll be posting on my channel until next time good luck with your exams and have a nice day