IPv4 Addresses and Subnetting - CompTIA Network+ N10-006 - 1.8
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- เผยแพร่เมื่อ 29 มิ.ย. 2024
- CompTIA has RETIRED the N10-006 exam series!
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The calculation of an IP subnet is a relatively straightforward process, and in this video you’ll learn how to use binary math to calculate the network address, broadcast address, and device addresses on an IP subnet.
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As a deaf guy studying subnetting for network+ I really, really appreciate you adding CC to this video! Keep it up!
My fiancee is deaf and I didn't realize how many you-tubers don't do this until I watched videos with her.
It is automatically generated CC
@@haofu1673 no, there is a transcript version on this video
This is one hell of a presentation. You can get hired as a Network Admin if you understand just this video.
I have watched around 9 different videos on IPv4 and this video is by far the most comprehensive and easy to understand subnetting and CIDR.
Professor Messer, I cannot THANK YOU enough for this fantastic video. I'm studying for the 007 and this has been, without a doubt, the best video I've come across on how to subnet. It's taken me days to figure it all out but it's finally clicking and I'm answering practice problems with ease. Not sure how I stumbled across a video from your 006 series but boy am I glad I did. Thanks again
I must admit that I watched this video last year when starting my preparations for the exam. Since that point, I've tried to learn several different other methods to make subnetting easier...such as using various charts. Now that I'm about to take the exam, I wanted to go back through your videos for a refresh. After viewing this instruction set, something just clicked in my brain. Thanks for the videos.
How did you do on the test?
This is absolutely incredible, understanding subnetting has always been a grey area for me until I watched your videos on the topic a couple times, and something just clicked. I've had so many professors FAIL to teach this to myself and classmates, but I understand it all now. Now, to just pass my security+ exam. Thanks Dr. Messer!
Excellent instruction. Thank you for clarifying something that I've found mysterious since my first LAN parties in the mid 90s.
Calm, collected, clear and complete. Excellent.
Thank you so much for being so clear and concise on how your are explaining the information. I really appreciate this. I have finals coming up and have been really confused and the way you explained subnetting is a game changer.
Life saver - Your way of teaching is very clear, you are awesome!
This looks like the one video to see if one wants to know the IP subnetting. Thanks for your great work with all your courses!
Thank you so much for explaining subnetting bit by bit. It really helped with my learning pace and the examples were a great AHA-moment for me!
I cant tell you how much this video helped me. I have watched another video and tried figuring this out in a book. I made a terrible mistake when I was calculating . I was counting from 0 and forgetting to take off the -2 for the network address and broadcast address. Thanks again. I was on your live broadcast today for your Network+ Study group, but had to cut to cut it short. Was a lot of fun. I am going to try to make it on your Security+ Study group as well.
Extremely helpful tutorial! Thank you Prof Messer.
There are many IT lecturers on the www.Sir,You are the best.
These videos are so clear. Extraordinarily helpful.
Thanks for the video, really useful. Subnetting has always caused headaches but I'm starting to get a grip on it after watching this.
Thank you Thank you Thank you Thank you Thank you. OMG. IDK how many times I can say thank you. INFINTELY GRATEFUL.
excellent video and very well presented. nice speed of delivery and very clear.
Finally, after watching this video, I understood subnetting... Thank you!!!
You're the best !!! Keep up the good work . Thank you so much.
Great explanation and easy to catch up. Thank you!
Very well done. Thank you Professor!
Thank you I needed this to listen to at work
Thank you so much Professor ! This was extremely helpful .
Thanks a lot for the explanation, it's help and simple
thank you Professor - excellent, I think I finally have it now!
Wow this was a damn good illustration!
huge difference without the glasses and goatee. XD almost thought i jumped to a different youtube account. great content and lessons!
you saved my life. thank u so much!!
thank you so much for this video! its the only one that helped me understand subnetting. taking my network+ in a few weeks.
Did you pass?
@@efteapea69 yessir!
@MikeShinnery Awesome!
Genius....you're a national treasure 👍👍
Amazing , much appreciated
This is extremely helpful!
great explanation, thanks
thank you for your work
Great video
It took me time to understand this because you used up the whole octet but this should be able to work with numbers like /26 /18 correct?
So, I understand the whole bitwise method, discussed at 3:38, but my question is regarding figuring out the network addy / subnet addy by bringing down all 0's or all 1's to determine the broadcast addy. It seems like there is not any actual "calculation," but that we simply bring down a 0 for the network addy and bring down a 255 for the broadcast addy. Is that correct? Because if we were performing the bitwise calculation, the last octet for the broadcast addy would have been 165, which we know it can't be for a broadcast addy.
Thank you!
I love you. Ty so much
Thanks, appreciate it.
Hi Professor. I'm so grateful that you put up this information on TH-cam. It has really helped me understand and remember information that my mind has been resistant to absorb from dry textbook material. I'm wondering if the broadcast address is always meant to have
x.255.255.255 in a classful Class A address,
x.x.255.255 in a classful Class B address,
and x.x.x.255 in a classful Class C address.
Am I understanding that correctly? I'm not clear on CIDR calculation. For example, if the it was /31, would the last octect always be the same value that I could memorize? or would there be a mathematical process I would have to use each time to determine this value?
+PDCCSF Videos All CIDR notation tells you is how many 1's are in the address or basically how much of that value is eaten up by the network address. /31 network is 31's with one zero in last octet.
I think I understand the host ranges given ONE network address... I want to see the network ranges disregarding the host numbers.... if I get that I will feel much more confident
Is CIDR and BGP Routing aggregation bot are same? please help me with some examples.
Where does a /25 get 2 networks from? I know you're borrowing 1 bit. That give you 2 combinations I assume(10000000 and 00000000)? But isn't 00000000 a /24? Besides that I'm finally starting to grasp this. Its taken me 3-4 times to watch this and I'll probably watch it more.
As always a fantastic video, but do I need to worry about bitwise AND? You can tell without doing any of the math at all by the CIDR notation or ipv4 subnet mask which is the network address and which is the broadcast. If you told me to find the network address and broadcast address of this address: 10.31.14.21 I would know immediately because it is within the range of 1-126 that it is a /8 network and the net address is 10.0.0.0 and the broadcast is 10.255.255.255. Am I missing something?
We no longer use class-based subnetting, so a 10.31.14.21 address could have any subnet mask. For example, I use a 10.1.10.0/24 address in my studio.
Oh I see where I made my mistake, just went over my head for some reason. Thank you sir.
How did you arrive at 65534 number of host at 8:54. i understood how you got 254 on the example before but little confuse as to how you go to 65534
+MrJamkev the last 16 bits from the subnet mask, are the host bits. 1111 1111. 1111 1111. >
The 0's = available host bits, so 2^16 = 65536 - 2 = 65,534. As he mentioned, the minus 2 = network address (10.11.0.0) and broadcast address (10.11.255.255), which are not usable 'host' addresses..
Question: on 6:34 mark, why is that the subnet mask is 255.255.0.0? isn't it suppose to be 255.0.0.0 since 10.11.12.13 falls within the CLASS A? or the network administrator can freely choose whatever the subnet mask is?
The class-based subnet masking was replaced with classless subnet masking in the 1990s. A network administrator can subnet with as many bits as they'd like.
How do the number of bits from the broadcast translate to the number of hosts? For example 8:43 he has 16 bits and gets 65,534
Sasha Ivanovic 2^16
It is 2^16, like Marshall says. However, to understand it further, look into Base 2 number system. It's essentially how you calculate binary.
How did he come up with the number 65534?
Sorry I don't understand how did you get the network numbers based on the subnet mask and CIDR? Like for /26, how did you know that it has 4 network? I hope you can help me understand this.
Thanks!
/26 is a class C IP address (24bits for network id and 8 bits for host ID), with 2 of the host bits becoming subnet bits (so now 24+2 bits for network + subnet id, then 6 bits for host ID). With 2 bits to calculate subnet ID you end up with four possible combinations: 10, 11, 01, 00. You can work this out yourself with any subnet mask, or you can use a cheat sheet for a quick answer
So basically the total numbers of combinations = # of networks right?
Clearly understood! But only problem that remained is Binary Math. It takes ages for me to convert decimal into binary or vice versa. Is there any way/s to master this conversion? :(
There is no easy way except learning the base 2 math. So 2 base 0 is 1, 2 base 1 is 2, 2 base 2 is 4, etc. It makes this process muuuuuch easier, check out other videos on subnetting and they'll get into base 2 math and it's a lot clearer
Just add
How did you get 165 Professor? That part confused me.
The Professor is using that IP Address as an example to work with. In an exam, you would be given enough information to answer a subnetting question. This may include an IP address, Network address, subnet mask etc
why's the broadcast on 15:45 .63 and not .64?
I'm showing the conversion from binary to decimal, and 00111111 binary is 63 decimal.
For the most part; I understand how to obtain the network address, the broadcast address and even the host address range. However I am having difficulty trying to find the number of host that can fit on a network. For example on the slide that starts on 8:08, it was determined that the number of host that can fit on a network was 65,534 and I cannot figure out how you obtained that number.
11111111.11111111 = 65,534 (I have tried the following calculations, X = incorrect)
255+255 = 637 (X)
255*255 = 65,025 (X)
Can someone help me, I am breaking my head against the wall..
That refers to the number of different values that could be used for those bits in the octet. Each octet has 8 bits and the way a computer counts is either on or off (1 or 0). If you have 2 bits, you can have up to 4 values. Either 00, 01, 10, 11. Now if you have 4 bits then the number of possibilities increase by a lot. You could have 0001,0011,0111,1111,1000,1111, etc. So, when he has 65,534 number of host, the computer can count higher by using more bits which lets it have 65534 different values. It can count all the way up to 65,534 since it has more "fingers" to count on.
It's 2^16. Ignore the dot between octets. Each place value is a power of 2.
I feel it should be 2^15 though, because the first place is 2^0. Anyone know why we use 2^16 instead?
Why doesn't each octet range from 0 to 256? It breaks into 8 bits 32 times
With most things inside the computer, you start counting with 0.
0 through 255 gives you 256 possible addresses.
Oh right is it because .0 counts as an address?
Thank you Professor Messer! Also, I'm looking at an IP address that ends with a /28. Why does the subnet become 255.255.255.240? How was this calculation done?
Jerry Lee, the slash mask (/28) is another way of representing a subnet mask. The number 28 indicates the number of network/subnet bits (1's) turn on in a 32 bit mask. To see this in action, simply write out 28 ones in groups of 8 (11111111.11111111.11111111.11110000) and convert each octet (group of 8 bits) into decimal using the binary numbering chart. The fours zero's were added to indicate the remaining bits are host bits.
But why are subnet masks needed in the first place? Seems an unnecessary complication. Just give everything on the network a unique IP address and that's that. Subnets don't mean you can have two machines with the same IP address, so what problem do subnet masks solve?
It would be functionally impossible to build a routing table that could keep an updated list of every other IP address in the world. Instead, we group IP addresses together into subnets and tell our routers where a group of devices resides.
This is similar in idea to a zip code or postal code. Instead of every city knowing the addresses and streets for every other city, they ship the mail to the closest zip code and the local mail carrier takes it from there.
what how did he get 65,536 ? ? Adding bits together would be 256 x 2 if there's 16. Soooo where did this 65 THUSAND come from ?
2 x 2 to the 15th power (32,768) = 65,536
@@joshuamoe5485 why not 2^15? I'm confused where the 16th power comes from if the first value is 2^0?
Jess Leighton
He's using this chart he made
2^8 2^7 2^6 2^5 2^4 2^3 2^2 2^1
256 128 64 32 16 8 4 2
2^16 2^15 2^14 2^13 2^12 2^11 2^10 2^9
65,536 32,768 16,384 8,192 4096 2048 1024 512
So he see there's 16 one's for the host and decides to look at his cheat sheet, he uses the power of 2 to double the amount of every time.
ex. 11111111 = 256 and we minus 2 for the Network Address and the Broadcast Address, which would leave us with a total of 254 Host available or usable.
I hope this helps and doesn't make it more confusing than it can be.
@@joshuamoe5485 binary begins with 2^0 =1, so 8 bits should equal 255 (2^7 + 2^6 + 2^5 + 2^4 + 2^3 + 2^2 + 2^1 + 2^0).
Still confused why he starts at 2^1. :/
@@joshuamoe5485 I suppose the binary 11111111.11111111 equals 2^16 minus 1... maybe thats why...