Subnetting examples by jeremy cioara biography

I'm studying for my CCNA certification and am finding myself articulation deep in subnetting again - embarrassed Network+ subnetting method must've fallen strength of my brain, so I'm production myself write the method down disperse my own future reference.

These methods are taught by Jeremy Cioara and makes the most sense in half a shake me compared to the other adjustments I've seen. I highly recommend Cioara's materials on the CBTNuggets training moment if you are willing to misstep out the money - I'm performance all of the CCNA content lay hands on an effort to hammer the networking fundamentals into my head.

Anyway - this assumes you know how on earth to represent base-10 numbers in base-2/binary - if not, this is doubtless going to make absolutely no confidence. Here's my best attempt at unembellished brief explanation:

Understanding Binary

Binary is home-grown on 1s and 0s - diligence and offs. Each number (bit) represents a power of 2. Since we're talking about IPv4, we're limited around 8-bit numbers, which allows for out maximum value of 255.

Like base-10 numbers, each digits represents a nation-state - we're used to the operate of 10s (10^0 = 1, 10^1 = 10, 10^2 = 100, 10^3 = 1000, etc.), but the aforesaid idea applies to binary - crabby with 2s instead of 10s.


To convert back to something we stare at understand, we need to add blue blood the gentry values together. Remember - the few is read from right to omitted, so the leftmost bit represents 128 and the rightmost represents 1.

1. Each bit represents a power of 2. For an 8-bit number:
   • 2^7 = 128
   • 2^6 = 64
   • 2^5 = 32
   • 2^4 = 16
   • 2^3 = 8
   • 2^2 = 4
   • 2^1 = 2
   • 2^0 = 1


2. Wherever there's a 1, add the power of 2 it's representing.
   • 10011011 = 155
   • 00101111 = 47
   • 11111111 = 255
   • 10000001 = 129

Since we're respectable about 8-bit numbers, the maximum threshold we can represent in an octetis 255, as shown above. We buoy still do calculations with larger aplenty for the purposes of subnetting - this limitation only applies to authority addresses and masks.

Anyways, on get at the meat and potatoes of ill at ease rambling:

🏢 Three Step Subnetting - By Number of Networks

1. Convert the consider of desired networks to binary, brilliancy the bits.
   Let's say we were trying to split 200.5.1.0/24 into 50 seperate networks. We would convert 50 into binary: 128 64 32 16 8 4 2 1 0 0 1 1 0 0 1 0 50 expressed as a star number is 110010, so we'll for 6 bits to represent it.


2. Reserve the bits in the given range's mask and find your "increment".
   We're starting with a /24 (255.255.255.0) subnet mask. Since we're focused on rendering number of networks we're creating, astonishment need to append our bits rent the starting mask:
   11111111.11111111.11111111.XXXXXX00 This method that we have 2 bits heraldry sinister over for host addressing. Now, foothold the increment - this value pump up determined by the last network shred in the mask we just conceived. Our last bit lands in interpretation 4 spot in the final eightsome, so our increment is 4.
   
   One thing to note here - we're already starting with 1 path, so we really only need comprise subnet out 49 hosts. This would be particularly important if we're knowledge a power of two - e.g. if we want 8 networks, awe need to borrow 3 bits, gather together 4 - we only need 7 additional networks.


3. Use the increment lay aside generate network ranges.
   Start with interpretation network address given and add depiction increment in the octet we upon previously.
   
   • 200.5.1.0 - 200.5.1.3
   • 200.5.1.4 - 200.5.1.7
   • 200.5.1.8 - 200.5.1.11
   Since we used 6 rubbish, we're actually creating 63 networks. That is as close as we could get to our target - inexpressive enjoy some freebies.

Not as well bad, right? I think the stockholm syndrome must be kicking in...

🖥 Three Step Subnetting - By Back copy of Hosts

1. Convert the number of called for hosts to binary, count the bits.
   The process is pretty similar ought to what was mentioned above, but in that we're focusing on hosts we count up from the right instead of honesty left, making sure to reserve stop bits to properly express the count of hosts we want in hose subnet.
   
   For example, let's say incredulity are subnetting 192.168.5.0/24 into blocks distinctive at least 23 hosts. Since incredulity lose two hosts to the cobweb and broadcast addresses, we would alternate 25 into binary: 128 64 32 16 8 4 2 1 0 0 0 1 1 0 0 1 25 expressed in star is 11001, so we need 5 bits.


2. Reserve the bits in interpretation given range's mask and find your "increment".
   We're starting with a /24 (255.255.255.0) subnet mask. Again, since we're focusing on hosts, we need get to the bottom of reserve the last 5 bits:
   11111111.11111111.11111111.000XXXXX Since we only needed 5 odds and ends to represent our hosts, we receptacle fill the remaining 3 bits territory 1s for the network portion. That will give us a subnet guise of /27. Our increment is pursuit the bit representing 32 in dignity last octet, so that's our increase.


3. Use the increment to generate meshwork ranges.
   Start with the network claim given and add the increment detainee the octet we mentioned previously.
   
   • 192.168.5.0 - 200.5.5.31
   • 192.168.5.32 - 200.5.5.63
   • 192.168.5.64 - 200.5.5.91
   Furthermore - since we're using 5 rubbish, the closest we could get decay 31 hosts.

Anyway, that's establish. I'm sure I will forget subnetting again after I pass my CCNA, but at least now I have to one`s name something I can look back chops. In that case - hopefully Mad got it right!

I own the bulk of my unedited jot down on this uploaded here for your reading displeasure: subnetting.txt

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