How IP Addresses Work | Network Fundamentals Part 4

Welcome to the fourth part of the Network Foundation series. This video looks at IP addressing, and how it works. This is critical information for anyone new to networking, or studying for CCNA or CCENT exams.
We start at the beginning, with what IP’s look like, and why. Understanding binary is your friend here! ( • Learn Binary and Conve... ).
Did you know that IP addresses are two addresses in one? Yes, it’s true! An IP includes the host address, as well as the address of the network it resides in.
Speaking of networks, we have changed how we address them over time. One of the early methods was to use classes. Perhaps you’ve heard of class A, B, and C networks?
But this has its limitations. So, we also have classless networks, or CIDR (Classless Inter-Domain Routing). This introduces a new concept: The subnet mask. Now we can break up networks as we see fit!
The next video will take this further, as we look at IP Addresses in Depth.
The CCENT/CCNA study guide (affiliate): click.linksynergy.com/link?id...

[@victostore2298]

Showing the answers to the quiz immediately after will aid more understanding.

[@ariefsaferman]

9.3.4.47 = class A 203.42. 62.1 = class C 103.88.77.22 = class A 151.10.13.55 = class B 222.2127.16.4 = Class C Just look at the first octet number when the range of every class A = 0-127 B = 128 - 191 C = 192-223 D = 224-239 E = 240-255

[@meethpanjwani3227]

thanks man

[@SalmanMalik-1234]

Thank you so much

[@ajaysharitra8310]

Thanks for the Huge Help Man !!!

[@chijinduegbo5640]

Thanks

[@jaccckky8978]

Thank you very much

[@tonywang7933]

The more I watch this series the more it baffles me how on earth I scored 84 on my 4th year university networking course yet still have so many details falsely understood, and how fortunate and grateful I'm finding these well explained videos. Thank you

[@amberkatz1680]

I can't get over how good your videos are. You really made me believe in myself because finally I understand these topics which I've been struggling with. Thank you so much!

[@NetworkDirection]

Thank you, I really appreciate the feedback. Hopefully their getting even better!

[@hodsh1]

Amber, would be interested to know what qualification are you studying for and what your career aspirations are?

[@Jijarugen]

bro deadass subnet masks have been the bane of my existence and then suddenly you come along and get me understanding in 15 minutes??

[@NetworkDirection]

I like to hear this 😀

[@ZakirKhan-vb9ds]

After hours of reading and watching videos, never thought it would be so simplified

[@parasmyname784]

Thank you so much bro. You taught me things I never go to learn in college. God bless you and wish you a great luck for your future endeavours

[@leroyrowe93]

This is wonderful content, i really love how you mentioned equations to make it simpler to comprehend

[@LoveUnconditional777]

The best CCNA Series on KZbin! So clear and concise. Your video series has provided great explanations of Network Security. It is much appreciated.

[@NetworkDirection]

Wow, thanks!

[@LoveUnconditional777]

@@NetworkDirection You're more than welcome.

[@tube-dude77]

FANTASTIC video, although the last part still a bit difficult to make out. Gonna watch the next video and see what happens lol

[@NetworkDirection]

Thanks. The next video will help explain more

[@mrberty2020]

Easy to understand videos, again fabulous work. Thank you!

[@technoultimategaming2999]

I've watched 25 minutes out of 1hr 10 minutes of my lecturers video, where he explains sub netting and you did it in 15 minutes. Your video uses a lot of logic, as in 255.0.0.0 obviously shows it's a class A 255.255.0.0 shows it's B... it's the power of presentation that shows me this. And it's the power of presentation that allows me to learn the same thing much faster. Thank you

[@azatkadyrov3634]

You have by far the best networking explanation videos out there. I have watched alot of them and also tried to read the books. But none of those pervious explanations are as clears as yours. Thank you kindly

[@NetworkDirection]

This is feedback I love to hear! Thanks!

[@xiaobai435]

i would say books are clearer though

[@AMan-yo3sy]

Thanks so much for these videos, they are incredibly helpful demistifying these vague concepts

[@rakshitks7850]

You are just awesome..... Keep up your good work You have made the explanation very simple and easy to understand.... Thanks a lot dude

[@NetworkDirection]

You're very welcome! More coming. TCP and UDP are next!

[@MrFireworks2]

are you serious, I'm starting to intern at Microsoft right for networking and all I can say is THANK YOU FOR SAVING ME HAHA. These videos are EXCELLENT for review.

[@kimanikelvin7393]

This guy should be protected at all costs great work. Can you do a DWDM video series?

[@smilingphoenix6225]

please explain also this areas like DWDM-SD-WAN technology......, how and why are they important and what is the reason for using them

[@PezhvakIMV]

finally a tutorial i was searching for, THANK YOU!

[@NetworkDirection]

Good to hear!

[@aamirkhanmaarofi9705]

Wawo ! Never thought these concepts would be this much easy. You are doing excellent, I appreciate.

[@NetworkDirection]

And I appreciate your comment, thanks!

[@timothykoba2975]

Wonderful explanations and videos. Thanks so much!

[@animepussy8356]

Your content is invaluable. TAFE CyberSec may now be more than a pipe-dream for me.

[@ndayizeyewilly1664]

Million thanks for all this videos i enjoy learning a lot from you thanks again

[@MetalMeek]

Wonderful vid, finally sat down in earnest to begin studying this morning. I can muddle through binary, IP conversion, and subnetting at least a BIT now. :)

[@NetworkDirection]

Glad it's helping!

[@doctordoctor1800]

Keep up the good work great job done to explain for us thank you alot

[@celiodealmeida1539]

You are doing a great job! I’m using your video tutorial to prepare for my ICND1 exam. Appreciate your effort.

[@NetworkDirection]

Hope you do well in the exam!

[@motocomputer]

Thanks for the easy to follow explanation.

[@NetworkDirection]

You're welcome Akhil! I'm glad that you have found our video helpful! We have more Network Fundamental videos coming so stay tuned. 😀

[@kumikohigurashi5366]

You've made my future and that of my family much better, thank you

[@produdeyay]

Just pointing out a few things i noticed 1) on 6:42, class C is typed as class B 2) on 8:23, 172.16 vs 172.17 the first 16 bits for these 2 should be 172.16 = 1010 1100 0001 0000 172.17 = 1010 1100 0001 0001 instead of 1010 1101 as shown in the video for 172.17. 3) on 12:21, the subnet is on the 2nd number (i.e. for 172.16.0.1, the number 16 is highlighted). Since the first number is 172, I would assume this is a Class B network, therefore shouldnt the subnet number be the 3rd number (i.e. for 172.16.0.1 the subnet should be 0)? I am just starting out, so not sure if I am correct. Also thank you for such wonderful and well made videos!!!!!

[@NetworkDirection]

Hi Produdeyay, you are absolutely right! I really appreciate that you are putting the effort into this. I wish I could say that this was deliberate to see who is paying attention but unfortunately typos happen.😀 Have a great day!

[@thebrokenchords8329]

@@NetworkDirection hey i would just like to add that the BIGGEST MISTAKE was 6:03 As the example is being given of a class C type address which is wrong . 130.2.3.4 is not a class C address ,it is a CLASS B type address.

[@ferdinandjohnson2359]

produdeyay s S sssf seas tsfastsFF

[@iyedbouazdia3594]

@@thebrokenchords8329 you're god damn right it is. I've noticed that too. I'm glad I'm not the only one :)

[@sebastianmacchi6802]

Yep! That's right! Also at 6:28 the limit for the class C should be 223.255.255.255 (not 223.255.255.0, since the last 8 bit can also go up 'til 255 --> 1111 1111)

[@penicksf]

These are great videos. Your production is fantastic! Keep it up.

[@NetworkDirection]

Thanks!

[@vladyslavutkin8543]

13:54 because 30 means we have only 2 bits so 172.16.2.1 is okay because 1 = 0000 00[01] but 172.16.2.20 is not okay because 0001 01[00] we need more bits not 2 but at least 5 so subnet should be 27. Am I right?

[@jeffb587]

this is the answer i came up with. sounds right to me!

[@jepoy1639]

Nah fam thats the wrong answer

[@Qasimumar86]

thank you sir you have really worked hard to make it understand

[@mitch4069]

Best video on this I've seen

[@NetworkDirection]

Thank you!

[@farrukhfreakkid]

99% of these videos are amazing and tons of info, 1% bad is maybe giving the answer after the question instead of going to a website every. Just my opinion, one can argue your method is better for learning which i see that point too. Amazing nonetheless

[@Jazzadrin]

Thanks for these videos, loving them. They are very clear and the visuals make it much easier to understand. I'm hoping watching these and reading my text will help me get ready for my mid term next week. Do you have any content on understanding subnetting and subnet masks? That is the area I am most confused about so far

[@Jazzadrin]

Like, you have explained the concept here... but in my class in expected to be able to answer a bunch of questions about subnetting and I still don’t really understand it very well. Oh well, just gotta keep digging in. Thanks again for your videos

[@NetworkDirection]

Yep, a bit more in this series, and more videos currently in development

[@kvr24611]

8:35 9.4.3.47 is a class A and would have last 3 part as the host address 203.42.62.1 is a class C and would have last 1 part as the host address 103.88.77.22 is a class A and would have last 3 part as the host address 151.10.13.55 is a class B and would have last 2 part as the host address and 222.127.16.4 is a class C and would have last 1 part as the host address

[@iyiolapeter6554]

this is a gold mine

[@TopNotch770]

Great videos! Thank you very much!

[@tristanbradleymusic]

Excellent description sir!

[@ElreyRayo]

Awesome tutorials!

[@ryanoleary4468]

Love this so much, thank you for making these!

[@NetworkDirection]

You're welcome!

[@user-qv7on3dl9y]

Hi there question regarding Classful addressing at 5 min 08 seconds. We were taught in my course that it's the hosts that get a -2 ie 16,777,216 hosts minus 2 is 16,777,214. Allowing for Network address and Broadcast address respectively. So same applies for B and C dropping 2 from the total hosts calculated.

[@claritstv]

Thank you for sharing this Information.

[@NetworkDirection]

My pleasure! Thanks for watching.

[@thomaswalther7276]

Very helpful video. At time 6:44 ist should be "Class C" in the last of the three lines.

[@javierthewish]

Very cool video. Keep it up!!!

[@ballajalloh974]

Wow Becoming networker is my dream i hope this will help greatly.

[@SergioGarcia-gd6ti]

Amazing explanation, as always...

[@NetworkDirection]

Thanks!

[@franciskiriba8142]

hey i just love the way you are explaining. also do something on ubiquiti devises parameters eg what does CCQ mean?

[@akshayhiremath4584]

Loved it! Perfect

[@NetworkDirection]

Thank you!!

[@geogmz8277]

I really like your style of explaining these subjects.. Keep them coming man.. I hope you do one of ~ipsec~ or MPLS either way I'll be happy.

[@NetworkDirection]

Thanks! You can get some IPSec here:kzbin.info/www/bejne/anq1lpmbj5ipr7s I'd like to do something on MPLS in the future. I'll need a lot of research before then :)

[@geogmz8277]

Oh right! You already did the IPsec one I saw it the other day and did not watched it but doing it right now.

[@NetworkDirection]

Hope you like it. Let me know what you think

[@NetworkDirection]

Get the Quiz answers here: networkdirection.net/labsandquizzes/quizzes/how-ip-addresses-work/ The CCENT/CCNA study guide (affiliate): click.linksynergy.com/link?id=RL4E*8CmbSY&offerid=145238.2445867&type=2&murl=http%3A%2F%2Fwww.ciscopress.com%2Ftitle%2F9781587205804

[@maxwellstylo7906]

I love A+ hardware and im trying to get into networking, but the ip addresses has always been my hindrance. When it comes to the math I guess I get overwhelmed easily. Oh well, I shall keep trying. Thank you for the informative vids. Gonna have to re watch this one 3 times though lol, no fault to you though.

[@NetworkDirection]

Don't give up! You'll get there with a bit of repetition and practice

[@uweguevara3651]

In the subnetmask You're talking about 1 for the network and 0 for the hosts. Wouldn't it be more correct to say 1 for the Subnets and 0 for the devices. Example: For a very little SOHO wouldn't it be correct to put the subnetmask 255.255.255.240 ? E.g. with 4 workstations, a switch, a router and a printer? Thanks and regards.

[@fetenetulu241]

excellent teacher long life!!!

[@NetworkDirection]

Thank you

[@lahorimunda18]

Hi, thank you for making this video. I am a little confused on 2 points; at 3:23 it states the network has 256 networks, but at 4:54 the same example, it says 128 networks. Am i missing something?

[@AMan-yo3sy]

Hey, This is because of the reserved networks I think. The class A IP address scheme thingy is set up in such a way that it forces the first bit in the first octet to be a 0. This effectively rules out 128 networks, because that specific bit holds a value of 128. It does make me wonder why those are locked and what they are being used for then, because surely they won't be wasted?Anyway, Im not too good at this, so excuse the poor wording.. just trying to help

[@randomnesslite]

There was 256 networks on the old system at 3:23 , so to allow people to have more than just the 256 networks they changed it so there were classes that allowed more networks on the same 4 sets of bits (bytes). So if you think that Class A - E have to share the whole pizza (all the available numbers), Class A (which is limited from 0.0.0.0 to 127.0.0.0) gets half the pizza (which is at 4:54). But to make sure a host knows it's Class A the first bit is set to 0 (like a Post Code) . If you take the first byte 0.0.0.0 and turn it into binary -> 0000 0000 and the first 0 is always the same (so its class A) then the highest value it can have is 0111 1111 which is 127 in base 10 (normal numbers). This means that there can only be 128 networks in Class A

[@jojogojo9318]

Great video👍👍

[@prakashmc2842]

Miga Arumai! Valthukkal!

[@NetworkDirection]

Thanks!

[@snoo333]

wow, learned a lot thanks.

[@NetworkDirection]

So glad you did, thanks for the comment!

[@1106896]

Hello, These are amazing videos for the network concepts, I would like to make sure my answers are correct, the link you provided for the answers are not direct enough, is there a way where I can check my answers for the quiz for all of your videos. I want to make sure I am correct.

[@itsdoofyjax]

You the best.....No cap

[@NetworkDirection]

Thanks @thedoofyworld! Im glad you liked our videos!

[@Comment_-nw2rp]

If you want a quick overview of CIDR and want to skip the classless routing, skip to 8:47

[@Yubbygucci]

Sir very good video help alot ❤❤ which books do you recommend to learn more about network on 2023

[@LunnieyNescense]

Hi, I notice that in the example of CLASS C 6:00 you wrote 130.2.3.4 as an example but the range of Class C supossed to be at 192.0.0.0 - 223.255.255.0 I know that it's just an example to show which part of the network address and host address but am I missing something here?

[@antoniokaram8189]

You are right, he pointed it out in the comments saying it was a typo

[@Heatlifer305]

Thank YOU!!

[@NetworkDirection]

You're welcome!

[@unixware6453]

THANKS !

[@NetworkDirection]

You're welcome!

[@tanzeelrehman929]

can someone explain how many hosts are actually left and how to work it out, honestly beautiful videos but i get confused at some bits like 6:20 when he says 256 hots left but he has written 255. Which one is it and how would i work it out? how would i know if lets say 255 is reserved and 0 is reserved, or is it the case that they are always reserved

[@thilinaalagiyawanna3680]

Thank you very much

[@NetworkDirection]

You are very welcome! Thanks for watching!

[@heartborne123]

is it some continuous adv of your web site?

[@stormwaker]

7:27 answers are: 9.4.3.47 - A 203.42.62.1 - C 103.88.77.22 - A 151.10.13.55 - B 222.127.16.4 - C

[@iyedbouazdia3594]

hey, can you please tell me why you chose those answers because I can't quite wrap my head around them :(

[@stormwaker]

@@iyedbouazdia3594 Let's take take 203.42.62.1 as an example. You take first octet so 203, translate it to binary so that's 11001011 (if you don't know how Google "Repeated Division-by-2 Method") and then check if it starts with: 0 - then it's class A 10 - then it's class B 110 - then it's class C 1110 - then it's class D 1111 - then it's class E Here it starts with 110 - so it's class C.

[@SalmanMalik-1234]

thank you so much

[@iyedbouazdia3594]

@@stormwaker thanks, I really get it now.

[@benn30ify]

Thanks for this, now I can practice with an example to work from! Cheers!

[@raducumihaicristian]

What if we have the IP 224.150.10.0? The first octet would be 11100000 which cannot be categorized as class A, B or C IP. What about all the IP's of which the first bits of the first octet are not 0 or 10 or 110? Also my second concern is why would we use the concept of a subnet mask? I mean we are using two IPs. One is the IP that describes the network Id and the host ID and the other IP is used for the subnet mask. Why can't we use the IP of the subnet mask as the Network ID and the other IP for the host?

[@paulaganbi5236]

hello, I have tried calculating the 16,777,215 figure at 3:33 but to no avail. how did you arrive at this figure? Thank you. Enjoying your videos so far!

[@NetworkDirection]

Here's how I did it: 1. Open windows calculator, and switch to programmer mode 2. Click the binary button 3. Click on the bits 0 - 23 to turn them on 4. Look at the decimal number (it should be 16 777 215)

[@fedegroxo]

It's 256^3 i.e. the total number of distinct addresses that you can write with three octets (with each octet you can write 2^8 = 256 numbers).

[@milanmestka416]

Great vid, however @6:45 is a little typo, last class should be C instead of B. You say it right but slides has typo

[@NetworkDirection]

Nicely spotted! You're really paying attention! Yeah, I occasionally let a typo or two slip through.

[@DEDEPLDEDE]

cheers mate

[@NetworkDirection]

You're welcome!

[@matsiekoketso7532]

Thank you

[@NetworkDirection]

you're welcome!

[@th3gam3rsloung37]

I'm as blank as a paper, but it's slowly starting to make sense to me👍

[@bulentemremmo6913]

I guess there is a problem at 6.14. 130.2.3.4 ip adress given to us has been converting incorretly. Converting 130 from decimal to binary should have been 1000 0010 instead of 1100 0001

[@debbiec855]

Best tutorial ever !

[@NetworkDirection]

Wow, thanks!

[@vtrandal]

Okay, this is helping me. Thank you. How can I ask questions or comment on an answer to one of your quizzes? I just became a Patron to look at the answer to a quiz question [the one at 13:31 (Quiz 4: Why is the Device in Network A Unable to Reach Network B?)]. My comment on this question: It seems the network diagram could be a bit clearer to show the left router "belongs" to the left IP network and the right router "belongs" to right IP network, yes? Or no? Do routers "belong" to IP networks? It's not clear from the diagram which IP network they belong. Why don't both routers belong to the middle (30 bit subnet) IP network? I would sincerely appreciate an explanation, because I've been around networking for awhile without understanding how it works in detail.

[@hamdha_zai554]

Where can I find the answers for the questions given here???

[@chiraggupta1557]

Can someone please tell the answer to the last quiz?? Is it because the last 2 bits of the 2nd router are both 0 and only they constitute the host address..?

[@cmyjones]

Maybe it's another typo, or maybe I don't get it yet, but how @6:27 the example IP for the Class C address is 130.2.3 when it's said that it starts only from 192?

[@NetworkDirection]

Yep, a typo. I think I need to rerecord this one...

[@cmyjones]

@@NetworkDirection hey hey that's drastic, maybe just a couple of overlays

[@eathonslambert3968]

would you ever do lessons on server fundamentals?

[@NetworkDirection]

Thanks for the suggestion. However, I'm focusing on networking for now (both in my career and on this channel), so I don't think there will be any server videos in the near future. I really do appreciate the suggestions though

[@bostjan3000]

at 11:50, how do you know that is a class b network split into 256 smaller ones and not just a normal class C network?

[@Somerandomdude-ev2uh]

Hi, Any chance you worked out the answer to this?

[@nic1411]

because the actual network is 172.16.0.0 which is a class B 255.255.255.0 is just the subnet mask, not the actual IP-address, I believe...

Hi one question. What do you mean with the "fixed bits"? I mean like in 06:16. "130" is not represented by 1100 0001. Rather it would be 1000 0010. I dont get the point. Besides this great work. Thank you.

[@NetworkDirection]

In the original 'classful' type of IP addressing, the first few bits represented the class. At 6:16, the first three bits are '110', meaning that this IP must be class C. However, don't focus on this too hard. Focus more on how Classless IP addresses work

[@arinjayagrawal8434]

When you say the first portion is used to network, what exactly do you mean by a network. Like a LAN?

[@nekdo9590]

Yeah, it could be LAN. Internet is a computer network that is divided into smaller networks by routers. You can think of router as a border between two and more networks.

[@NetworkDirection]

The network in this case, is the part of the IP address, called a subnet, that identifies a LAN. In your network you may have multiple LANs, for example, a server LAN, a workstation LAN, etc

[@athinaf8955]

In the ranges of the classes, why do the not finish at an address with the form: x.255.255.255? For example, in the class B, the given range is 128.0.0.0 to 191.255.0.0 Why?

[@dimasalang3221]

Because the first 2 bits are not used. If you convert the binary of class B, the range is only up to 191.

[@vtrandal]

Can anyone give an example of two devices in the same subnet but not in the same IP network? [Concerning 12:08 in the video.] For classless networks doesn't "same subnet" imply "same IP network" ? At first glance yes, but then these subnets can be reused somehow, yes? If so then it's this reuse of subnets that expands IPV4 addressing greatly .AND. allows for devices on the same subnet to be part of a different IP network, yes? No? And to respond to your question at the end: I agree that classless networking + superneting is the future (and has been) for awhile!

[@shifarraamulugeetaa4700]

it is good continue

[@NetworkDirection]

Will do!

[@uweguevara3651]

13:54: Because Bits 24-29 are interpreted in a different way by the 3 networks? The little one in the middle interprets them as part of network address, where as it's an internal one?

[@RicardoValero95]

@Uwe Guevara I think that the mask /30 is 255.255.255.252, which leaves only 4 hosts available, so the range is .0 - .3. So 172.16.2.20 is out of range? This is my guess

[@aszh]

@@RicardoValero95 can you explain this to me in more detail if possible ?

[@clayandro]

@@aszh Ricardo is right. The .20 address from the right router does not fit in the IP range from the /30 subnetmask.

[@zzaarrker]

6:43 you whrite B on class C . I like youre videos you are smart :)

[@rodionlim7069]

What does it mean at 12:25 when it says that devices in the same subnet but separated by a router are unable to communicate with each other?

[@NetworkDirection]

It means these are two separate networks. Devices in different networks can't communicate with each other directly. Instead, they can send their traffic to the router, which forwards the traffic on their behalf.

[@panzerofthelake1623]

11:20 now im confused at this part, why exactly did the third octet turned from 0 to 255 and why 256 instead of 255??? I need a much simpler and detailed explaination please, thanks.

[@NetworkDirection]

Because of the subnet mask. This controls which part of the IP address is the 'network' part. We're only showing the network part on the screen. an 8-bit number has 256 values. But, counting from zero, that's 0 to 255

[@relax_user7230]

I still don’t understand where you got the 256 from? 11:54

[@richardtheranger5214]

Thank you for this, I really do like these but you don't explain Subnetting and how you get the values that well. I have to go back and watch this again to see if it'll click. But overall a great video, thanks

[@NetworkDirection]

You’ll see some subnetting in the next part

[@hobermallow5841]

Yes, I don't understand this either. I just subscribed and am even more confused regarding Quiz 3a and the .240. It seemed like the concept was about 255 and 0 but then 240 gets thrown in there and I don't see how that equates to 20 bits.

[@hobermallow5841]

Conversions to binary and how many bits that yields to the network in a Subnet mask (I think): 128 = 10000000 (1 bit for the network) 192 = 11000000 (2 bits for the network) 224 = 11100000 (3 bits for the network) 240 = 11110000 (4 bits for the network) 248 = 11111000 (5 bits for the network) 252 = 11111100 (6 bits for the network) 254 = 11111110 (7 bits for the network) 255 = 11111111 (8 bits for the network)

[@sonnyvieng3516]

Little typo at 6:44 When you say "Class C", it's listed as Class B again. Just so there's no confusion if anyone else caught this

[@uweguevara3651]

12:56: We have to count the 1s and calculate 2 exp n. So in the first example we have 2 exp 16, in the 2° we have the maximum of 2 exp 20 subnets. The number of addresses per subnet we calculate like this: 2 exp (number of 0s), what is 2 exp 16 in the first and 2 exp 8 = 256 in the second case. Right?

[@JotaEseUveA]

Shouldn't be: Class C from 192.0.0.0 to 223.255.255.255 instead 223.255.255.0? Thanks in advance for such a great class.

[@Dan-bm1ug]

The problem at 13:40??? Is it the you cant have .20 at the end of an IP the is /30 because the max you can achieve with binary is .3?

[@Faust_ZA]

yea as soon as he started explaining subnetting my brain crashed

[@NetworkDirection]

That'll happen, just give it time

[@tushitapatel5782]

Would anybody be able to help answer the question at 13:47, please? I don't understand what belongs here and why there are two addresses on either side of the routers. What does that mean? Why can't router A direct the message to router B? TIA.

[@tushitapatel5782]

I understand that it probably has to do with 172.16.2.20 does not belong in the networks that 172.16.2.0/30 supports, but it is not clear to me why there are two hosts on either side of the router and what they mean.

[@noone6896]

The right router, shouldn't it be 172.16.2.2 (not 172.16.2.20)? Bcauz if it has subnet mask /30 it can have only 3 hosts. thank u for ur help!

[@kylecheng7155]

why does subnet mask /30 only have 3 hosts?

[@noone6896]

172.16.2.0 is network itself. and 172.16.2.1/2/3 is 3 possible hosts ... in my opinion

[@forevolution88]

I think it would mean that only 2 hosts would be allowed, as hosts cannot be all 0's or 1's, so it would either be 2.1 or 2.2