Fixed-Length Subnet Mask (FLSM) - Subnetting Mastery - FLSM and VLSM Appendix Part 1 of 2

[@PracticalNetworking]

All the videos in the series and the problem generator is available here: SubnetIPv4.com Want to learn the Fundamentals of Networking? www.practicalnetworking.net/index/networking-fundamentals-how-data-moves-through-the-internet/ Studying for the CCNA? Here are free resources to help you learn: www.practicalnetworking.net/index/ccna/ If you enjoyed this content, don't forget to show your support by liking, subscribing, and sharing this content amongst your peers. That would really help me out. Thank you!

[@RonLarhz]

If you start at /21 How is 32 >= 50 ip address? Shouldn't it be /27 with 64?

[@adelnaseer1388]

@@RonLarhz x32 + x16 + x8 + x4 + x2 = 62 number of ips

[@aneegashfaq3697]

This series is the best!!!! I think this should be showed in universities!!! Great job PRACTICAL NETWORKING!!!

[@PracticalNetworking]

Thank you. And... I agree! =)

[@j.d.837]

Your whole subnet series has been immensely helpful. It's taken me a very long time for this stuff to click but it's clicking. Thank you.

[@PracticalNetworking]

Hey JD, so glad you enjoyed it =) Glad it is finally clicking!

[@keivankhamoushchi]

after 1 year know i can call my self subnetting master. thank you so much sir for a real helpful content . i used so many methods , someone told me i show u subnetting in 1 second somebody other ways but you maked me master of subnetting now . thanks a lot

[@TheTechguyonline]

really enjoy the simple way you explain complex topics. for someone who has worked in networking a very long time its nice to see someone explain it in a way everyone can understand. Keep up the great work.

[@PracticalNetworking]

Thanks for the kind words, Preston =) I appreciate you.

[@scottspa74]

This video is phenomenal! I actually consider myself to be pretty good at subnetting, and can generally do it in my head pretty quickly, but I had never been exposed to these types of questions, and so never thought about how to solve them. This was excellent. Nailed it once again, Ed.

[@PracticalNetworking]

Glad you enjoyed it Scott. Cheers!

[@spiffykimmy]

Hands down the best subnetting series I have found. I am currently taking the CCNA course through Cisco and I have watched TONS of videos on subnetting over the last two months, and you nailed it my friend. I get it now. I am going to get your networking course as a companion to explain the information I don't understand in my class (which is plenty🙂). Thank you so much!

[@olanddevo]

Just want to say that of all the study guides out there ive encountered this by far is the most helpful one. As a person who has always struggled with math, Your methods of explaining sub netting awakens clarity in my scattered mind. Thank you for making these videos!

[@davidmoore775]

This video series is teaching me everything I need to know about subnetting

[@PracticalNetworking]

That was exactly it's goal! Glad it worked, Dave. Cheers !

[@adedejiemmanuel1]

I am always back here because I cannot get enough of your trick. Thank you.

[@PracticalNetworking]

[@PracticalNetworking]

After watching this video, are you convinced you could nail any FLSM question you get? =) Don't forget to watch the next video which discusses VLSM! kzbin.info/www/bejne/l56uqpmYnJp6aLM

[@craigcj5953]

I have a question that basically asks, "If I start from a /16 network, how many subnetworks can you make that have 1000 address, seeing as the group sizes only go up to 128 for /25, I don't know how to solve this.

[@PracticalNetworking]

@@craigcj5953 Video 6 and 7 in the Subnetting series teach you how to solve for "number of IPs" for subnetworks bigger than /25. Give those a watch =)

[@kiethlouielatigo9717]

Thanks, Ed. I now easily understand subnetting because of your videos. May God bless you.💌

[@bluebadgersec]

This is true legendary territory here. I can't thank you enough, Ed!

[@illuminate143]

This is great, the logic is so cohesive and the chart makes it so easy!

[@PracticalNetworking]

So glad you enjoyed it =) Thanks for watching!

[@pascal0868]

Professionally done. Well explained in clear English.

[@PracticalNetworking]

Thank you, Pascal =)

[@jesseriddle-jansen2556]

Thank you very much for posting this. I feel very confident with FLSM now and am moving onto your VLSM video. Great explanations and great job.

[@PracticalNetworking]

You're welcome =). Glad you enjoyed the videos and feel good about FLSM!

[@SakshiKumari-lc5wb]

Bruhh why are you not famous? Hands down the best video ever... Please cover more CCNA concept... I wish you good health.

[@PracticalNetworking]

Thanks for the kind words. I have plenty of CCNA content here: www.practicalnetworking.net/index/ccna/ Enjoy!

[@MrDavidson231984]

Thanks for the efforts in creating these videos.This is really informative and helpful.Waiting for the next one.

[@PracticalNetworking]

You're welcome =)

[@hossayyaqobzai5096]

you saved my life with these videos

[@mukangwakalonda7726]

At first i was learning network like the lost cat with full of confusion and headaches but here my head get baptized clear and eyes opened and realize why i am here

[@Cloud_with_lois]

😅do cats get headaches?

[@Shake_Well_Before_Use]

Thank you so much. Ive watched your ACL playlist and upto this video on this playlist and i gotta tell you its helped so much. Thank you again for this.

[@G-H-0-S-T007]

Thank you So much for all these details and examples

[@joaofernandes1774]

Amazingly clear and simple! Thanks so much😊

[@manojitdas5110]

Thank you sir for simple explanations.

[@PracticalNetworking]

You are welcome

[@mpasaa]

Fantastic tips! I had another chart memorized that was similar and had the number of hosts listed too but your cheat sheet is much more streamlined and efficient. And as you mentioned in one of your videos if the number of hosts is required and it is the larger numbers they would need to provide a calculator anyway so that info isn't really needed on a written chart.

[@PracticalNetworking]

=) Glad you liked this chart. Yea, I've come across other "cheat sheets" that were _huge_. It would take a whole page to write out and just was not practical for something to quickly jot down when you go for a test.

[@jaelski1217]

Now this is a very fast method! I was just wondering how I could apply the techniques from the last subnetting videos, when given an IP then given a required number of hosts or subnets. Really thanks a lot man!

[@PracticalNetworking]

Glad to help, Jaelski. I'm glad you enjoyed this series =)

[@carlosmalovini]

Sir, you're absolutely magnificent... God bless you and Thank you!

[@PracticalNetworking]

=) Thanks for the kind words, Carlos. And you're absolutely welcome! Glad you enjoyed these videos!

[@manuelchiocchetta5842]

Grazie.

[@PracticalNetworking]

Thank you for supporting this channel, Manuel. Cheers !

[@mahdirahmani9556]

Why there's no ipv6 You are the best teacher for networking so plz create ipv6 subnetting mastery also

[@isdmg4129]

Thank you for the quality videos!

[@PracticalNetworking]

You're welcome !

[@UndieingLust]

Could you do a series for IPv6? Really good stuff

[@PracticalNetworking]

I'd like to. Yes.

[@sumanthprithvi]

Hi. I've been following videos on networking basics fervently over the past few months and yours has become the guide rail for me. Thanks for making complex ideas approachable. Btw, in the example, around 4:20 the cheat sheet begins at /25 and has 64 networks at /26, whereas in the question, it starts at /21, so shouldn't /22 already contain 64 networks, by /23 we should only have 32 networks. Is this right or have I not understood yet?

[@PracticalNetworking]

Something you're missing here. The 64 is the # of IPs, not the # of networks. And every time the CIDR changes by 1, the number of networks double (or half if going the other way). For example: - a /24 includes 2 /25s - a /24 includes 4 /26s - a /24 includes 8 /27s - a /25 includes 2 /26s - a /25 includes 4 /27s And so on. Hope this helps.

[@imjinaah]

hope you're having a great day, because I am XD thank you so much! :D

[@PracticalNetworking]

You're welcome =)

[@MuditJain-g6i]

thank you for your videos.i had just one doubt.At 4:25 as it is a /21 means it will be in third octet so shouldn't we check no of ip address by the formula 2^(CIDR-21). Thanks again

[@PracticalNetworking]

Yes... if you're trying to calculate the # of IP addresses. BUT in this case, we're figuring out how many subnetworks fit inside the /21, and we can use that with the doubling effect described in the video.

[@MuditJain-g6i]

@@PracticalNetworking thanks for the reply

[@MusaTheGamer]

You're back!!!!!

[@PracticalNetworking]

=)

[@adedejiemmanuel1]

Hi, Referencing your lecture at 1:41, I guess we cannot increase the CIDR more than /32, right? Am I wrong? Please tell me.

[@PracticalNetworking]

Correct. An IP address is only 32 bits, so /32 is the "highest" CIDR that exists (for IPv4).

[@espartaco2028]

IF, and I do curse the Cisco training material, but IF ¨they¨would have simply taken the ¨it can be a 0 or 1¨ for the binary bits conversation and then said, ¨and that bit can be either a network bit or a host bit¨, and gone from there...ALL of this would have be elementary, looking back. But they didn´t. They made a religion out of it and complicated the hell out of it. Thank you for demystifying the process exponentially...literally.

[@PracticalNetworking]

Thanks for the kind words. Yes, I too never liked how Cisco taught it, and don't get me started on the "borrowing bits" narrative -- can't stand that.

[@StylistecS]

@@PracticalNetworking yeah it confuses me as well and it also takes longer.

[@brusslee1814]

Do I need to know past this video in the subnetting mastery playlist for ccna?

[@PracticalNetworking]

Yes

[@Vikbytes]

Simply fantastic

[@yel-hadd]

that was very helpful! thank you

[@PracticalNetworking]

You're welcome!

[@diligenzz2032]

genius explanation thank you sir!

[@PracticalNetworking]

You are welcome!

[@anniejames5955]

Why we do subtract from /26 for the second problem (easy method)

[@PracticalNetworking]

The question asks for subnetworks with 50 usable IP addresses. The smallest size subnet that satisfies that requirement is /26.

[@mundoin5583]

Any plans to do Packet tracer Labs videos ?

[@PracticalNetworking]

Not at the moment. But I'm open to the thought. Is that something people would want to see?

[@ytfamily000]

@@PracticalNetworking Yes!

[@jesseriddle-jansen2556]

@@PracticalNetworking Yessssssssss

[@justme-iz7ec]

fantastic, thank you so much

[@PracticalNetworking]

You're welcome !

[@aileenquinto4165]

I thank GOD I found your channel here in KZbin 🙏. I’m so much grateful about your teaching! You’re so great teacher sir! Thank you so much for sharing your knowledge and tips to easily understand the subnetting 🙏

[@8080VB]

Do we need to study this for CompTIA network+

[@PracticalNetworking]

Yes. Definitely =)

[@rashidbestry]

amazing 🥰

[@admin_e]

thank very much

[@PracticalNetworking]

You're welcome, Erkin!

[@saedaden9722]

brilliant thank u very much

[@PracticalNetworking]

You're welcome. Glad you enjoyed them, Saed.

[@ndybinaziz1279]

If you start with a /21, how many sub-network would you create that could contain 50 IP address? Question. Where this/26 come from to subtract /21?

[@PracticalNetworking]

I explain that right around 4:00 of the video. The question asks for 50 IP addresses and the cheat sheet discussed in videos 1-7 of this subnetting series shows you how to determine that a /26 can contain 50 IP addresses.

[@admin_e]

👍👍👍

[@seesoftwr8032]

IMO- That just me. I believe sometime go with the very old "bit" should be ok here. Sometime bits are more confusing (with endless 1111 and 0000) than helping but here it should be ok (even without showing endless 1111 and 0000). Example at 3:50. We can translate the prob and solution: IPv6 is 32 bits. We consume/reserved 21bits for subnet so 32-21= 11bits. With 11bits left how many subnets of 50 hosts? -we know that 50hosts (after quick binary calculus or table) are contain in 64hosts so need 6bits. So 11-6bits host = 5 --> 5bits left for network --> so 5bits = 32 subnets and NEW total bits used for those 32 subnetmask are 21+5 = /26. - if /20 then 32-20= 12. 50host --> 64host = 6bits. 12-6bits= 6 for subnet = 64subnets --> new subnetmask 20+6 = /26 -- BUT the point is to UNDERSTAND and there is way some people will click and other will not! So as long as we are agree to the result lol (To understand; it is not necessarily the faster way to solve a problem but maybe the long detailed way. "I didn't understand... Can you draw it to me?")

[@Suiiiijohn]

doesn't explain why you deduce that /26

[@junfengfan]

10.10.10.10 8 subnet .how to do ？

[@Travel-mi4iq]

sub Net = 10.0.0.0 First Host = 10.0.0.1 Last Host = 10.255.255.254 Broadcast IP= 10.255.255.255 Next Net = 11.0.0.0

[@RonLarhz]

Your time saving trick(previous series) is actually not easy to rmb. Time to figure out equals time to calculate the old school way. Lol

[@PracticalNetworking]

They will become easier with practice.

[@CH-vv2hr]

I do not know why so many people have such trouble explaining this

[@PracticalNetworking]

Agreed!

[@tahersadeghi6773]

Confusing Big time.

[@manalalkhadar]

لا منو قال متوهقه ويايه افتح يوتيوب🌷

[@mikailshakes4514]

I'd prefer not to put music as it can be a bit distracting

[@caleb_gonsalves]

This is so confusing, so wrong, and there's an easier way to do it! Each IP address has for most of the time a NETWORK, SUBNET, and HOST portion, which the NETWORK portion is typically defined as a CLASS A, B, and C and cannot be changed or manipulated. For Example, they will give you a 172.16.0.0/16 this is a Class B for definition, so they can also give you this example of 172.16.0.0/18 this will mean that the NETWORK portion is until the 16, the remaining 2 bits are the SUBNET and the remaining 14 bits until 32 are for the hosts. So, this example (172.16.0.0/18) as to how you see it is 2^2=4 available SUBNETS and 2^14-2=16,382 available host. So, from the example of the video, if you start with /18 and you need 100 SUBNETS, you simply use 2^ of what number gives me 100 or more subnet? Then you realize is 2^7=128 so you count 18+7=25. I hope I helped.

[@PracticalNetworking]

Hello. Thanks for chiming in. I intentionally created these videos omitting the concepts of Binary and Classful networking. Binary, because I feel it adds unnecessary confusion. And Classful because it's been a legacy concept for years. I wrote about that here: www.practicalnetworking.net/stand-alone/classful-cidr-flsm-vlsm/

[@carlosmalovini]

Honestly, not at all ...

[@caleb_gonsalves]

@@PracticalNetworking OMG, Binary is necessary and must be understood before even trying to do subnetting. It's like trying to understand TCP/IP but unnecessary to understand The OSI model, it's just nuts dude. Every networking book will guide through this legacy terms so you can easily understand the very in-depth terms. Thanks for the comment, this let me know how ignorant can you be by saying such a thing!

[@caleb_gonsalves]

@@carlosmalovini I assume you don't have a networking background, do you? because this is not the way you initially learn to do subnetting and that why I am saying it's confusing. If you did had a networking background and come to this to refresh your understanding of VLSM you'll find this very confusing, but for a new guy this may be the way to kind of grasp the idea but it's no the correct or easier way to do it. Believe dude if you go to the networking world without these basic and necessary concepts (binary and classful) in mind and not really learn to do it the proper way you are going to be screwed up and confused when you face an IPv4 issue. Let me know!

[@jaelski1217]

I think this videos he made is for you to solve subnetting faster. I mean in the exam you have to be fast right.

[@bkkk3868]

Poor Visiblity of video

[@pmanolak]

Hi Ed. I am bit confusing about the number of subnets. Found in one book that the number of subnets are indeed 2^N, but told also about the number of valid subnets which are 2^N-2, because the first and the laat subnets are invalid. I found this on the book CCNA Portable Guide by Cisco Press, at the first chapter in all editions until Fourth. Strangely removed from fifth edition which is for 200-301.

[@syedaquib1082]

Sir you're living Networking legend🫡🫡🫡🫡