in previous videos we've gone through the process of manually converting an IP address in subnet Mass to Binary performing the proper calculations and converting it back to decimal we also looked at a shortcut called the magic number method that allows us to very quickly calculate the same information without performing that binary to decimal conversion this shortcut is the 7c subnetting shortcut and this is the process that I use when calculating subnetting on an exam this is a process very similar in structure to the magic number method and indeed most of the shortcuts you find will have some variation of this within them the part that's very different to the 7sec subnetting is that there is no math involved you don't have to perform any calculations to determine a magic number and everything you need will be predefined in the chart that we create at the very beginning you'll find that the only math you end up doing is adding and subtracting the value of one to be able to calculate the first IP address and the last IP address this is one of many available shortcuts to help you with the subnetting process and I highly recommend you look at a number of different ones to find one that works for you this 7-second submitting process works equally well whether you are online taking this exam and using the online whiteboard or if you have a physical whiteboard in front of you at a testing center the proc process of calculating the subnet is really about splitting the network into smaller pieces you may start with a Network that has 256 total hosts available or you might break it up into smaller subnets such as a 128 where you might have two different subnets a 192 which separates it into four different subnets a do 224 that separates it into eight individual subnets and so on the core to the 7c subnetting process is creating this chart we will start with a chart that defines the subnet masks this allows us to very quickly determine what the decimal mask might be if we're given a cider block notation and vice versa you can see this is very similar to the Chart you would create with the magic number method we're simply performing the same math on the 7 second subnetting we also have a networks column you would calculate that by starting with the number two and doubling it all the way up until 256 and then you have an addresses column which starts with 128 and you would divide by two all the way down until you get to the number one and to help with the conversion between the cider block notation and the decimal mask we have a subnet mask in decimal column that we'll add in as well once you've created this chart you have everything you need to be able to calculate everything necessary for a subnet without having to perform any type of additional math if you're like me and you have problems determining what the start of a subnet might be on a subnet that has 16 hosts or 32 hosts you may want to write out those subnet boundaries into a separate chart so you can very quickly find what those might be during the process of Performing your calculations for example a Network that has 128 hosts per Network would have host boundaries at 0 and 128 a Network that has 64 IP addresses per subnet has Network boundaries at 0 64 128 and 192 and you can calculate similar boundaries for networks with 32 IP addresses 16 8 and 4 the 7c subnetting process is a four-step process the first step is to convert the IP address and the subnet mask to decimal this is necessary if you're provided the subnet mask in cider block notation but fortunately we have a chart that can very quickly translate between cider block notation and decimal the second step is to determine the subnet address this is something you may be a ble to do in your head or if you're like me you've written out that second chart that shows you where the delineations are for each individual subnet that same chart shows us what the broadcast address might be because we can simply look at the last address in that particular range and from there it's very easy to determine what the first and last usable IP addresses might be by adding one to our subnet address and subtracting one from our broadcast address let's use this process to subnet at 165 24512 18824 this sl24 needs to be converted from the CER block notation into decimal notation you may be able to do this one in your head very easily but you can also reference your chart by finding the sl24 you can see that our chart shows the sl24 is part of that third octet and it shows that that third octet will have a mask of 255 everything after that will have a mask of zero so performing that calculation means that our subnet mask is 255.255.255.0 now we need to calculate the network or subnet address if the mask is 255 we need to bring that address down and if the mask is zero we're going to Simply bring down a zero so if the mask is 255 we bring down the address and you can see in the first second and third octets the mask is 255 so we'll bring down the 165 245 and 12 and if the mask is zero we bring down a zero so in this example our Network Address is 165 245.20 to calculate the broadcast address we look at the subnet mask again and if it's 255 we bring down the address number if the mask is zero we use 255 in this example the first second and third octets all have 255 so we will bring down our address numbers as 165 24512 and if the mask is zero we bring down 255 so in this case the last octet does have a mask of zero and we'll put a 255 in that last octet for the broadcast address now that we have our Network address and our broadcast address it's relatively easy to calculate the first available IP address and the last available IP address to calculate the first IP we take the network address and we add one so that would be 165 24521 and the last IP would be the broadcast address minus one so that would be 16524 12254 there is the 7c subnetting process using our chart and using those simple rules to be able to define the network address the broadcast address the first available IP and the last available IP let's do another example that doesn't fall on those simple 8bit ranges of the subnet mask we're going to use the same IP address but with a different subnet mask in this case it would be 165 24512 18826 the first step will be to take the sl26 cider block notation and convert that Mass to decimal if we look at our chart we can find the sl26 and we can see that it is the 1 2 34th octet and in that fourth octet we want to put a 192 decimal that means that our subnet mask is 255.255.255.192 which which is the conversion from the sl26 if we look at our chart where it has the sl26 or the 192 you can see the number of addresses is 64 and since our IP address has an 88 we can look at the different blocks in those 64 ranges to determine where the 88 might be and in this case it's in the range that starts with the block of 64 we'll follow the same rules we had before if the mask is 255 we're going to bring down that address and if the mask is zero we're going to bring down a zero in this example we have three masks that are 255 so we'll simply bring down the address values for each of those octets in this last octet the mask is 192 if we refer to our chart we can see that we have that range of 64 addresses we look at our IP address of 88 and determine in which one of those 64 address blocks 88 might be and it's in the range that has 64 as its starting point this is what we're going to bring down into the fourth octet is that value of 64 to calculate the broadcast address we look at the subnet mask again and if it's 255 we bring down the address values if it's a zero we use 255 in this particular case our subnet MK does not have any zeros so we need to refer to our chart again we know that this is the range with 64 addresses per subnet and we know that 88 fits into that second block we know looking at the chart that the next block starts with a 128 which means that the broadcast address must be the one prior to that number so that would be 127 so the broadcast address is 16524 12127 and of course to calculate the first usable IP address we add one to our Network address so our first IP is 16524 12.65 the last IP address is determined by taking the broadcast address and subtracting one so that would be one 165 24521 126 we can perform the same shortcut with any IP address and subnet range let's take the example of 165 24512 18820 if we look at this address we take the sl20 and convert it to a decimal subnet mask we can determine this by finding the sl20 in our chart it is in the third octet and that third octet would be a240 so everything to the left of that will be 255s and everything to the right will be zeros so our subnet mask of a sl20 is the same as a 255.255.255.0 so we need to determine where the12 might be in our list that 12 fits between the 0er and 16 so it's this very first Subnet that we're going to look at in this particular range let's calculate our Network address if the mask is 255 we bring down the address and if the mask is zero we use zero in this case we have a 255 in the first two octets and a zero in the last octet so we simply bring down each one of those since we're looking at the range that has the dot 12 and we know that there are 16 hosts on each of these subnets then that 12 is in that range between 0 and 16 and the first number being zero means that that is our Network address and so we'll bring that down as our third octet this means that our Network Address is 165 245.000 to calculate the broadcast address we look at every place there's a 255 and we bring down that address so that would be our first two octets and if there is a zero as part of the subnet mask we use 255 and we'll bring down that 255 for the fourth octet since we have a 240 as the subnet mask in that third octet we need to look at our chart again and determine what number we would bring down since we know there are 16 addresses in each of those blocks we know that the next subnet will start with a 16 so one number prior to that 16 would be a 15 and the broadcast address for this subnet is 16524 15.2 255 now we can calculate the first available IP address by looking at the network address and adding one that would make it 165 2451 and we can calculate the last available IP address by subtracting one from the broadcast and that would be 165 24515 254 let's go through the process again with an IP address of 18172 2.77 sl11 the first thing we're going to do is convert that sl11 to a decimal mask and if we look at our chart we'll find the dot 11 is in the second octet and it has a value of 224 so our subnet mask is going to be 25522 4.0.0 on the same line as that subnet mask is the number of addresses and you can see in this particular example there are 32 addresses per subnet since at /11 is in the second octet we're going to look at that IP address to determine where it fits in those blocks of 32 IP addresses so if we were to look at our chart of these 32 address blocks we know that 172 fits in this range between 160 and 191 so to calculate the network address if the mask is 255 we're going to bring down the 18 that's in that block and if it's zero we're going to bring down zeros and since this block starts with a60 our Network address is 18.1 160.0 do0 to calculate the broadcast address if the mask is 255 we bring down the address and if the mask is zero we use 255 this means in the first octet we'll simply bring down the 18 and in the third and fourth octets where the mask is zero we'll write 255 in this third octet we'll go back to our chart and we know that's the range between 160 and in this case the next range starts at 192 therefore the broadcast address for the previous range would have to be 191 and to calculate the first and last available IP addresses we will add one to the network address and subtract one from the broadcast address meaning the first IP is 181601 and the last available IP address is 18.11 25525 let's perform one more calculation to see how well we've captured this shortcut we'll use the address of 18172 27717 if we go to our chart we can find the SL 17 is part of the third octet and it matches that 128 value as the decimal part of the Mask so if we were to write out the mask it would be 255.255 12280 if we were to look at our chart that /7 is on the same line as blocks of 128 hosts so we know that there were 128 IP addresses in each one of these subnets so let's calculate from there what the network address might be if the mask is 255 we will bring down the address value and if the mask is zero we will use zero to calculate the broadcast address we look at the subnet mask and if it's 255 we bring down the address and if the mask is zero we use 255 in this example we have subnet masks of 255 in the first two octets so we'll bring down those address values and we have a zero in the fourth octet so we'll use 255 in this example that value of 200 is in that third octet which puts in the second block starting with 128 and ending with 255 so in this case the broadcast address would be the last address in that block which is 255 meaning your broadcast address is 18172 255.255 and of course to calculate the first IP address we add one to the network address making it 18172 12281 and we calculate the last IP by subtracting one from the broadcast address making last IP 18172 255.255 as you can probably tell the key to the 7c subnetting process is being able to reference that chart so you might want to try writing this down in a chart if you're going to be in a testing center or you may want to try typing it into a notepad or word pad to see how quickly you can type it in if you're going to be taking the exam online if you go to a testing center you may find that the dry erase pin that they use may not allow you to make a very easily readable chart so you may want to bring your own pen make sure you check with the testing center that it's okay to bring your own fine tip dry erase pin into the test itself and whether your shortcut is the 7sec subnetting process the magic number process or any other process make sure you find the shortcut that works best for you and decide to use that for your exam