Welcome to Jeremy’s IT Lab. This is a free, complete course for the CCNA. If you like these videos, please subscribe to follow along with the series. Also, please like and leave a comment, and share the video to help spread this free series of videos. Thanks for your help. In this video we will cover all you need to know about ‘first hop redundancy protocols’, or FHRPs. This isn’t the name of a specific protocol, it’s a type of protocol, and there are three FHRPs you should be aware of for the CCNA. Let’s check the exam topics list. Here it is, topic 3.5, ‘describe the purpose of first hop redundancy protocol’, I think there should be an ‘s’ on the end there. There is no mention of configuration, so you don’t need to worry about about configuring any of the FHRPs for the exam. However, in this video I will show you basic configurations for one of the FHRPs, so you can try it out in the next lab video. Even if you don’t need to know the configurations for the exam, getting a little hands-on practice will help you understand how these FHRPs work. Here’s what we’ll cover in today’s video. First up, I’ll introduce the purpose of first hop redundancy protocols. Then I’ll introduce three different FHRPs. HSRP, hot standby router protocol. VRRP, virtual router redundancy protocol. And GLBP, gateway load balancing protocol. It may seem like a lot to learn about three different protocols in one video, but you just need to be able to make basic comparisons of each, you don’t need to know them in-depth. Finally we’ll spend a few minutes learning some basic configurations of HSRP, hot standby router protocol. After the quiz at the end of the video I will feature a bonus question from Boson ExSim for CCNA, a set of practice exams for the CCNA. I studied using ExSim when preparing for both my CCNA and CCNP exams, and I highly recommend that you do too. To get ExSim, follow the link in the video description. Okay, let’s get started. I used this same diagram back in Day 20 when talking about spanning tree protocol, to demonstrate the concept and importance of redundancy in networks. For example, if there is only one connection to the Internet and it fails due to a hardware failure or something else, these PCs will no longer be able to reach the Internet. In your home, losing Internet access for some time would be frustrating, but probably not a disaster. For most modern businesses, however, it would be a big problem. So, we can use redundant connections to the Internet like this. Notice I’ve added some device names and IP addresses in the 172.16.0.0/24 network to make things easier to talk about. Now if this connection fails PC1 can use this alternate path to the Internet. This could be, for example, a slower and cheaper connection that is only used until the main connection is recovered. But let’s stop and think about this, because it’s not so simple. In this network, let’s say R1’s IP address 172.16.0.254 is configured as the default gateway. So that means each PC is configured with the 172.16.0.254 address as its default gateway. So, anytime these PCs need to send traffic outside of the local subnet, they will send it to the default gateway, R1. But what happens if R1 goes down for some reason, perhaps a hardware failure? Fortunately, there is a backup router connected to the Internet, R2. But there’s a problem here. Can you identify the problem? Pause the video and think about it for a minute. Okay, the problem is here. The PCs’ default gateway is still set to .254, R1’s address. Although R2 is available as a backup, the PCs don’t know that R1 is down and that they should switch to using R2 as their default gateway. If a PC needs to send traffic over the Internet, it will continue to try to send the traffic to R1. So, how can we cause R2 to automatically become the new default gateway if R1 can no longer be used? That’s the role of a first-hop redundancy protocol, an FHRP. Here’s a brief explanation of FHRPs from Wikipedia. ‘A first hop redundancy protocol (FHRP) is a computer networking protocol which is designed to protect the default gateway used on a subnetwork by allowing two or more routers to provide backup for that address; in the event of failure of an active router, the backup router will take over the address, usually within a few seconds.’ The name ‘first-hop’ redundancy protocol is used because the default gateway is the ‘first hop’, the first router in the path to whatever destination the PC is sending traffic to. Here’s how FHRPs do this. The two routers share a VIP, a virtual IP address, for example 172.16.0.252. You configure the PCs in the network to use that virtual IP as their default gateway, instead of the actual IP address of R1. Now, the routers have to negotiate their roles with each other. How do they do that? They send multicast ‘Hello’ messages to each other, like this. Okay, so what roles did they negotiate? Well, one of them, let’s say R1, will become the active router. The other, R2, will become the standby router. Note that the actual terms, like active and standby, vary depending on which FHRP is being used, because as I showed you before there are a few different FHRPs. So, R1 is the active, meaning it will act as the default gateway for the network. R2 is the standby, meaning it will not function as the default gateway unless R1 fails. If R1 does fail, it will automatically take over the role as default gateway. So, let’s say we set up our FHRP here in this network, and now PC1 needs to send some traffic to a destination in another network. Here’s what PC1 is thinking. I need to send traffic to a destination in another network. My default gateway is 172.16.0.252, but I don’t know the MAC address yet. I will send an ARP request to learn the MAC address of 172.16.0.252. I haven’t mentioned ARP in a while in this course, but remember that it is used to learn the MAC address of a particular IP address. In order for PC1 to encapsulate the packet in a frame destined for the default gateway, it has to know the default gateway’s MAC address. So, PC1 will make an ARP request like this, saying ‘Hi 172.16.0.252. This is 172.16.0.1. What’s your MAC address?’. Remember that the ARP request message is broadcast. So, it will be sent over the network like this, reaching all hosts. Fortunately spanning tree prevents a broadcast storm by disabling some of the switch interfaces. So, both R1 and R2 have received the ARP request, and they both share the same virtual IP address, 172.16.0.252, the one in the ARP request. What happens now? Which will send the ARP reply? R1 is the active router and R2 is the standby router, so you can probably guess that R1 will send the ARP reply. And that is correct. R1 will send a unicast ARP reply like this. ‘Hi 172.16.0.1. This is 172.16.0.252. My MAC address is...’, and then it will tell PC1 the virtual MAC address. That’s right, not only is a virtual IP address used, but a virtual MAC address too. Each FHRP uses a different virtual MAC address, and I will introduce them later. So, the ARP reply is sent to PC1. Now PC1 knows the MAC address of its default gateway. So let’s say PC1 needs to send some traffic to the IP address 8.8.8.8, which is a Google server by the way. What will the source and destination fields of the frame and packet be? The source IP will be PC1’s, 172.16.0.1. The destination IP will be the Google server, 8.8.8.8. The source MAC will be PC1’s MAC address. And the destination MAC address will be the virtual MAC address used by the FHRP. The frame will be sent to R1, and then the packet will be sent over the Internet. Now what if R1 goes down? There is no default gateway for the network. But after a few seconds, R2 will think ‘I haven’t received any ‘Hello’ messages from R1 recently...I will become the Active router!’. So R2 is now the active router. But how does it tell the other devices to send traffic to it instead of R1? Note that the end hosts, the PCs, actually don’t have to change their ARP tables. The entry in the PC’s ARP table is like this, mapping the virtual IP address 172.16.0.252 to the virtual MAC address. So, what needs to be updated to make traffic start going through R2? The answer is the switches. R2 needs to make the switches update their MAC address tables. Remember how switches update their MAC address table. When they receive a frame they check the source MAC address field, and use that to update the information in the MAC address table. So, R2 needs to send frames with a source MAC address of the virtual MAC address. To do this, it will send ‘gratuitous ARP’ replies. Gratuitous ARP is probably outside of the scope of the CCNA, but here’s a very brief explanation. Gratuitous ARP messages are ARP replies sent without being requested. Normally ARP replies are sent in reply to an ARP request, but in gratuitous ARP, the ARP reply messages are sent without receiving an ARP request. Here’s another difference between gratuitous ARP and regular ARP replies. The frames are broadcast to the MAC address of all Fs, but normal ARP replies are unicast. Because they are broadcast, all switches will receive the frames and update their MAC address table. So, R2 will send gratuitous ARPs like this. They will be broadcast throughout the network, and again spanning-tree protocol will prevent a broadcast storm. The switches will then update their MAC address tables. SW2 will learn that it can now reach the virtual MAC address via this interface, SW1 will learn the same thing, and so will SW3 and SW4. Now R2 is the active router, and all of the switches have updated their MAC address tables. Let’s say PC1 wants to send traffic to the same Google server, 8.8.8.8, again. The frame and packet are exactly the same as before. Source IP is PC1’s, Destination IP is the Google server, source MAC is PC1’s, and destination MAC is the Virtual MAC. However, this time the frame will be sent to R2, which will send the packet out over the Internet. Now, what if R1 comes online again? Will it become the active router once again? No, it will become the standby router. Like I said about the DR and BDR in OSPF, FHRPs are ‘non-preemptive’. The current active router will not automatically give up its role, even if the former active router returns. However, although this is the default behavior, you can change this setting to make R1 preempt R2 and take back its active role automatically, so R2 will become the standby router again. Okay, so that was a basic overview of how first hop redundancy protocols, FHRPs, work. I haven’t talked about any specific FHRPs yet, but most of that information applies to all of them. Before moving on to explain a few specific FHRPs, here’s a quick review. A virtual IP is configured on the two routers, and a virtual MAC is generated for the virtual IP. Each FHRP uses a different format for the virtual MAC address, I’ll cover those MAC addresses in the next section. An active router and a standby router are elected. Again, different FHRPs use different terms, and some support what’s called an ‘active-active’ setup, with two active routers at the same time, but I’ll explain more later. Next, end hosts in the network are configured to use the virtual IP as their default gateway. The active router replies to ARP requests using the virtual MAC address, so traffic destined for other networks will be sent to it. It functions as the default gateway for the network. If the active router fails, the standby becomes the next active router. The new active router will send gratuitous ARP messages so that switches will update their MAC address tables. It now functions as the default gateway for the network. If the old active router comes back online, by default it won’t take back its role as the active router. It will become the standby router. This is like the DR and BDR in OSPF, they don’t give up their roles automatically even if another router is configured with a higher priority. But, in FHRPs you can configure ‘preemption’, so that the old active router does take back its old role if it comes back online. Okay, sorry for the wall of text. Before moving on to a few specific FHRPs, I recommend watching the previous section once more to make sure you understand the basics of how FHRPs work. Now let’s move on. N ow I’ll give a brief overview of three major FHRPs. The functionality of each is very similar, so this section will be quite brief, but make sure you learn these details for the exam. First up, HSRP, Hot Standby Router Protocol. HSRP is Cisco proprietary, so it only runs on Cisco devices. You can’t run it on Juniper routers, for example. In HSRP, an active and standby router are elected. These are the two terms I used previously, but you’ll see the next FHRP uses different terms. There are two versions of HSRP, version 1 and version 2. Version 2 adds IPv6 support, and increases the number of ‘groups’ that can be configured. You’ll see what a group is when we configure HSRP later. In our example today, there was just one subnet, 172.16.0.0/24, and one VLAN. But in situations with multiple subnets and VLANs, you’ll need to configure a virtual IP address for each subnet, because each subnet needs its own default gateway. Each of those virtual IPs is configured in a separate HSRP group. Anyway, as I said you’ll see how that works later. Remember how I explained that the routers communicate with each other by sending multicast hello messages? These are the addresses used. 224.0.0.2 for version 1, and 224.0.0.102 for version 2. It may seem not so important, but try to remember these addresses for the test. Next up, the virtual MAC address formats. These are tougher to remember, but make sure you remember them for the exam. Use the flashcards, try writing them from memory, whatever you have to do to remember them. So, version 1 uses 0000 0c07 ac, followed by the group number. So, in my previous example let’s say I configured the virtual IP address in group 1. If using HSRP version 1, what would be virtual MAC address be? It’s 0000 0c07 ac01, because the group number is 1. Now, HSRP version 2 uses the format 0000 0c9F Fxxx, again xxx is the group number. Note that 3 hexadecimal digits are now available instead of 2, so there are more group numbers available. Anyway, if group number 1 is used, what would the virtual MAC address be in HSRP version 2? It’s 0000 0c9f f001. One last point, in a situation with multiple subnets/VLANs, you can configure a different active router in each subnet to load balance. Remember what I said in previous videos about spanning-tree protocol? You can configure a different root bridge in each VLAN so traffic is load balanced over the switches. Well, when you configure multiple HSRP groups, one for each subnet and VLAN, you can configure a different active router in each subnet and VLAN. For example, R1 could be the active router in VLAN1 and standby in VLAN2, and R2 could be the standby in VLAN1 and active in VLAN2. This is probably beyond what you need to know for the CCNA, but let me briefly demonstrate the concept. Let’s say VLAN1 is assigned to hosts in the 172.16.1.0/24 subnet. PC1 and PC3 are in VLAN1. R1 and R2 have their own IP addresses in VLAN1, but they also share the virtual IP 172.16.1.252, which is used as the default gateway of the subnet. R1 is the active router and R2 is the standby router. Then, 172.16.2.0/24 is the subnet for VLAN2. PC2 and PC4 are in VLAN2. R1 and R2 have their own IP addresses in VLAN2, connecting to the switches using ‘router-on-a-stick’. They also share the virtual IP address 172.16.2.252, which is used as the default gateway for the subnet. R2 is the active router and R1 is the standby router. Now traffic can be load balanced over the two paths, VLAN1 using R1 and VLAN2 using R2 as the default gateway of the subnet, and each subnet has a standby router waiting if the active router fails. So, that’s a basic overview of HSRP. Although it can’t load balance within a single subnet, you can configure a different active router in each subnet so that traffic is load balanced between the routers. Let’s move on to the next FHRP. Next up is VRRP, Virtual Router Redundancy Protocol. Unlike HSRP, it’s an open standard, so it can be run on devices from any maker. Cisco routers run it too, so you can use either HSRP or VRRP. Honestly, in terms of functionality they are nearly identical, with just a few differences. Instead of an active and standby router, a master and backup router are elected. The function is the same, just the names are different. Master is equivalent to HSRP’s active, and backup is equivalent to HSRP’s standby. The IPv4 multicast address used is different as well, 224.0.0.18. Again, use the flashcards to remember little details like this. The virtual MAC address format is different, too. 0000 5e00 01, followed by the VRRP group number. Let’s try a bit more of a challenge. What if I configured VRRP group 200, instead of group 1. What would the virtual MAC address be? You have to convert 200 to hexadecimal. Pause the video to try that, do a Google search if you don’t remember how hexadecimal works. Okay, the answer is 0000 5e00 01c8. Hexadecimal c8 is equal to 200 in decimal. Just like HSRP, although VRRP can’t perform load-balancing for hosts in a single subnet, it can load balance between different subnets by configuring a different master router in each subnet. Here’s the same diagram as before, showing load-balancing between the two subnets. All that’s different is that ‘master’ and ‘backup’ are used instead of ‘active’ and ‘standby’. Before moving on, I just want to mention one point separate from FHRPs. Notice that all hosts in VLAN1 are in the same subnet, 172.16.1.0/24, and all hosts in VLAN2 are in the same subnet, 172.16.2.0/24. This is how subnets and VLANs are used. Subnets divide the network at Layer 3, and VLANs divide the network at Layer 2, and they work together, each subnet being its own VLAN. You might have noticed that throughout this course, but I just wanted to point it out. Before moving on to the last FHRP, here’s a comparison chart of HSRP and VRRP. In terms of functionality, they’re nearly the same. But remember the different terminology, multicast IP addresses, and virtual MAC addresses. Also remember that HSRP is Cisco proprietary, whereas VRRP is an open standard that can run on any network device that supports it. Next up, we’ll take a look at GLBP. The final FHRP you should be aware of is GLBP, Gateway Load Balancing Protocol. This one is a bit different than HSRP and VRRP. Like HSRP, it is Cisco proprietary, it only runs on Cisco devices. Here’s the big difference: it load balances among multiple routers within a single subnet. For example, if PC1 and PC2 are both in VLAN1, PC1 can use R1 as its default gateway, and PC2 can use R2 as its default gateway. This is different than HSRP and VRRP, in which all hosts in the same subnet must use the same router as the default gateway for the subnet. In GLBP, a single AVG, Active Virtual Gateway, is elected for the subnet. Then, up to four AVFs, active virtual forwarders, are assigned by the AVG, and the AVG itself can be an AVF also. Each AVF acts as the default gateway for a portion of the hosts in the subnet. So, load balancing is achieved within a single subnet. The multicast IPv4 address is 224.0.0.102, same as HSRP version 2. The virtual MAC address format is 0007 b400, followed by the GLBP group number and the AVF number. For example, what is the virtual MAC address of AVF number 1 in GLBP group 1? It’s 0007 b400 0101. So, the functions of GLBP are a bit more complicated than HSRP and VRRP, but for the purposes of the CCNA remember that GLBP allows multiple active routers to load balance traffic within a single subnet, and remember the multicast IP address and the virtual MAC address format. It might seem not so important, but for the CCNA exam definitely remember the IP and MAC addresses. Here’s that chart again, with GLBP filled in. If you remember the basic characteristics of HSRP, VRRP, and GLBP, and memorize the information in this chart, you’ll be ready to answer any questions about FHRPs on the CCNA exam. However, as a little extra, I’m going to show you some very basic configurations for HSRP, so we can try it out in a lab in the next video. Although configuring HSRP isn’t part of the CCNA exam topics, getting some hands-on experience will help you understand how it works. So let’s do some basic configurations for HSRP. To fit everything on the page and show the CLI at the same time I’ve simplified the network. We’ll be focusing on configuring R1 and R2 to use HSRP to provide a redundant default gateway address for the 172.16.0.0/24 subnet. I’ve already configured all of the interface IP addresses, so we just need to configure HSRP. Note that I’m using .254 as the virtual IP this time, instead of .252. So, let’s get started configuring R1. HSRP is configured directly on the interface, G0/0 in this case. Make sure you configure it on the correct interface, the one connected to the network it is acting as the default gateway for. HSRP is configured with the STANDBY command. I used the question mark to see what options are available. There are many more than this, but the one we want to use is this one, group number. Note that HSRP version 1 is the default, so the range of groups available is 0 through 255. If using HSRP version 2, this range would be 0 through 4095. Actually, let me show you how to change it to version 2. The command is STANDBY VERSION 2. If I check the STANDBY command again, you can see that the group number range is now 0 through 4095. This simple network is using just a single VLAN, VLAN1, so I chose HSRP group number 1. You don’t have to do this, it’s not a rule, but I like to match the HSRP group number to the VLAN number used for the subnet. Note that this group number does have to match between the two routers, that’s important. So, I used the question mark again to check the options available here. We’ll go over three. IP, PREEMPT, and PRIORITY. First up, you configure the virtual IP with this command, STANDBY, group number, IP, followed by the IP address you want to use as the default gateway. Then I used the PRIORITY command, as you can see the range is 0 to 255, and I set R1’s priority to 200. What does priority do? It’s used to determine which router will be the active router. The active router is determined in this order. First, the router with the highest HSRP priority in the group will become the active router. The default priority is 100. If the routers have the same priority, the router with the highest IP address will become the active router. In this case R1’s IP address, 172.16.0.253, is higher than R2’s IP address, 172.16.0.252. So, even without configuring the priority R1 would still become the active router, but I configured it anyway. Finally, I enabled ‘preemption’. Enabling the PREEMPT command causes the router to take the role of active router, even if another router already has the role, although the preempting router must have a higher priority or IP address. For example, let’s say R1 is the active router and R2 is the standby router. If an error causes R1 to restart, R2 will become the active router. When R1 comes back online, if preemption is not enabled R2 will remain the active router and R1 will be the standby. However, with preemption enabled R1 will take back its role as the active router, because it has the higher priority. Note that you only need to configure preemption on the router that you want to become the active router. Even if I don’t configure preemption on R2, R1 will still be able to preempt R2 and take back the active role. Now let’s configure R2. First up, I enabled HSRP version 2 on R2’s G0/0 interface. This is important, HSRP version 1 and version 2 are not compatible, so if R1 uses version 2, R2 must use version 2 also or there will be problems. Next I configured the same virtual IP as on R1, 172.16.0.254. The next two commands, setting the priority and preemption, are actually unnecessary. R1 already has a higher priority than R2, and preemption doesn’t need to be enabled on the standby router. But I configured them anyway, so the configuration is consistent between the two routers, but it doesn’t really matter. Finally let’s take a look at the output of SHOW STANDBY. This is the output from both R1 and R2, let’s just take a look at R1. First up, notice the HSRP group number of 1 and that version 2 is being used. The state is active, because R1 is the active router. Here the virtual IP address we configured is displayed. These two lines display the virtual MAC address, it’s the default one. Here are the HSRP timers. We didn’t configure these so they are the default values. Preemption is enabled, because we configured STANDBY 1 PREEMPT. Active router is local, because R1 itself is the active router. The standby router is 172.16.0.252, which is R2. And finally here is the priority value of 200 that we configured. If you want to take a look at the output of the command for R2 also, pause the video. Okay, that’s all we’ll cover about HSRP configuration, in the lab video we’ll get more hands on. Before moving on to the quiz, let’s review what we covered in this video. First I gave an introduction to the purpose and basic function of FHRPs, which is to provide a redundant default gateway for a subnet. Then, I briefly introduced three different FHRPs, HSRP, VRRP, and GLBP. Make sure to learn the basic characteristics of each, and use the chart to memorize their multicast IP addresses and virtual MAC addresses. Then I introduced some very basic HSRP configuratons. You probably won’t be asked about these commands on the exam, but getting some hands on practice will help you understand the topic, so in the next video we’ll do a simple HSRP lab, taking a look at preemption and such. Here are the commands we used. STANDBY VERSION 2, to configure the router to use HSRP version 2. STANDBY IP, to set the virtual IP address that will be used as the default gateway. STANDBY PRIORITY, to help control which router becomes the active router. And STANDBY PREEMPT, to cause the active router to take its role back if it recovers from a failure. Remember to watch until the end of today’s quiz for a bonus question from Boson ExSim for CCNA, by far the best practice exams you can get for the CCNA. You can get Boson ExSim from the link in the video description. Okay, let’s go to question 1 of the quiz. Which of the following is an HSRP version 1 virtual MAC address? A, B, C, or D. Pause the video now to think about your answer. The answer is D, 0000 0c07 acab. The HSRP version 1 virtual MAC address format is 0000 0c07 ac, followed by the group number, in this case AB. What is AB in decimal? It’s 171, so in this case HSRP group number 171 was used. As for the incorrect answers, options A and C are HSRP version 2 virtual MAC addresses, and option B does not follow any FHRP virtual MAC address format. Let’s go to question 2. Which of the following is a VRRP virtual MAC address? A, B, C, or D. Pause the video to think about your answer. The answer is A, 0000 5e00 010a. The VRRP virtual MAC address format is 0000 5e00 01, followed by the group number. What is hexadecimal 0a in decimal? It’s 10, so in this case VRRP was configured using group number 10. Option B is a GLBP virtual MAC address, option C is an HSRP version 2 virtual MAC address, and option D does not follow any FHRP virtual MAC address format. Okay, let’s go to question 3. Which of the following are valid VRRP router roles? Select two. A, active. B, backup. C, active virtual gateway. D, master. E, standby. Or F, active virtual forwarder. Pause the video to think about your answers. The answers are B, backup and D, master. A, active and E, standby are HSRP router roles. C, active virtual gateway and F, active virtual forwarder, are GLBP router roles. VRRP uses master and backup routers. Okay, let’s go to question 4. When the HSRP standby router becomes the new active router, what kind of messages does it send? Select the best answer. A, HSRP hello messages. B, gratuitous ARP messages. C, ARP request messages. Or D, ARP reply messages. Pause the video to think about your answer. The answer is B, gratuitous ARP. Some other answers are not totally incorrect, but are not the best answer, let me explain. In Cisco’s questions, at the end it usually says ‘select the best answer’. That’s because some of the options aren’t totally incorrect, however they aren’t the best answer. For example, option A is ‘HSRP Hello’. Routers using HSRP always send Hello messages. So, when the HSRP standby router becomes the new active router, it will continue sending HSRP hello messages, so A isn’t totally incorrect. However B is the better answer, because it only sends these gratuitous ARP messages when it becomes the new active router. How about D, ARP reply? I told you that gratuitous ARP messages are a kind of ARP reply, so D isn’t totally incorrect. However, B is the better answer because it’s more specific. So, when taking the CCNA exam make sure you’re selecting the best answer, even if some of the other options seem like they might be correct. Let’s go to question 5. Which of the following statements accurately describes HSRP? Select the best answer. A, it allows you to configure a different default gateway address on each end host. B, it allows multiple routers to load-balance traffic for hosts in a subnet. C, it provides a redundant default gateway address for hosts in a subnet. Or D, each router selects a unique virtual IP and MAC address. Pause the video to think about your answer. The answer is C, it provides a redundant gateway for hosts in a subnet. Although you can configure a different active router in each subnet to provide load balancing, it doesn’t provide load balancing for hosts in a single subnet. To do that, you would need to use Cisco’s GLBP, gateway load balancing protocol. Okay, that’s all for the quiz. Let’s move on to a bonus question in Boson ExSim for CCNA. Okay, here's today's Boson ExSim practice question. By the way, I noticed that you can zoom in on ExSim, so hopefully this is easier for you to read now. So here's the question. Why of the following statements are true regarding HSRP? Select two choices. Okay, so I'll let you read these options yourself. Pause the video here, read the options, and select the two correct choices. Okay, hopefully you got the answers. So let's check them. A, one router is elected as the master router, and all other routers are placed in the backup state. That is incorrect, master and backup, that terminology is used for VRRP, not HSRP. B, in an HSRP group only one virtual IP address is used, but multiple virtual MAC addresses are used. That is also incorrect. In a single HSRP group only one virtual MAC address is used. Okay, C. One router is elected as the active router and another router is elected as the standby router. That is correct, I believe, about HSRP. D, in an HSRP group only one virtual IP address and one virtual MAC address is used. That is correct also. I think, but let's check option E as well. All routers in an HSRP group can participate by forwarding a portion of the traffic. Okay, that is not true for HSRP, but it is true for GLBP. Okay, so I think C and D are correct. Let's click on show answer. And that is correct. So here is Boson's explanation, quite detailed. You can pause the video here if you want to read it, I highly recommend you do. They also have a reference to some Cisco documentation here that you can read online for free. And it states the category of the exam topics list, which is IP Connectivity. Okay, so that's an example question from Boson ExSim. Boson ExSim is a great set of practice exams for the CCNA. I used it when studing for my CCNA, and I also used ExSim for CCNP when I studied for my CCNP, and I highly recommend them. So if you want to get a copy of Boson ExSim for CCNA, follow the link in the video description. There are supplementary materials for this video. There is a flashcard deck to use with the software ‘Anki’. There will also be a packet tracer practice lab so you can get some hands-on practice. That will be in the next video. Sign up for my mailing list via the link in the description, and I’ll send you all of the flashcards and packet tracer lab files for the course. Before finishing today’s video I want to thank my JCNP-level channel members. Recently I’ve noticed an increase in the number of channel members, and I’m so thankful to all of you, both JCNA and JCNP-level members. Your support helps me keep making and releasing these videos every week, so I’m really grateful for your support. This is the list of JCNP-level members at the time of recording by the way, September 21st 2020, if you signed up recently and your name isn’t on here don’t worry, you’ll be in future videos. 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