Ccent - i cant sub net :(

randazz18

I cant sub net to save my life! does anyone know any tricks or shortcuts??

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ninjaturtle

Subnetting can be very frustrating, but once you grasp the concept you'll want more on the exam because it's easy points. Try to avoid the tricks and shortcuts at first. Learn the long binary way first, then start cutting corners to speed up your times. I strongly recommend Todd Lammle's CCNA book. He does an excellent job covering subnetting!

Just keep at it, you'll get it ...I promise!

Cheers,

RouteMyPacket

I've given several comprehensive approaches to subnetting. Here is a recent one

http://www.techexams.net/forums/ccna-ccent/103992-vlsm.html

Subnetting is a joke and you yourself will laugh later once you "get" it.

mooed_music

This is not a good explaination but I hope it helps.

Here's what I do. I just use my fingers. Say it's a /28 network. In my head I say 24. Then I place my thumb on the table and say 25. Then I place my pointer on the table and say 26. So on and so on till I get to 28. That leaves me on the ring finger. I've only ever memorized 128, 192, 224, 240 248, 252 in that order and 128, 64, 32, 16, 8, 4 in that order. Back to the ringer finger. Now I count again this time from 128 down to 16 (in this case) stopping once i get to the ring finger (again, in this case). This gives me the block size. Counting up till I get to the ring finger will give me the mask.

auxiliarypriest

mooed_music wrote: »

This is not a good explaination but I hope it helps.

Here's what I do. I just use my fingers. Say it's a /28 network. In my head I say 24. Then I place my thumb on the table and say 25. Then I place my pointer on the table and say 26. So on and so on till I get to 28. That leaves me on the ring finger. I've only ever memorized 128, 192, 224, 240 248, 252 in that order and 128, 64, 32, 16, 8, 4 in that order. Back to the ringer finger. Now I count again this time from 128 down to 16 (in this case) stopping once i get to the ring finger (again, in this case). This gives me the block size. Counting up till I get to the ring finger will give me the mask.

I finger subnet too! But I definitely agree with ninjaturtle and learn the long way to understand what you are doing first. The tricks will help with speed. Danscourses did a subnet tutorial it might help you out...Subnetting, Cisco CCNA, Binary Numbers -Part 1 - YouTube

Jon_Cisco

subnetting.net - Subnet Questions and Answers

Spend an hour practicing the answers here. After getting them wrong and seeing the correct answer a few dozen times it starts to sink in. Practice is the only shortcut I learned.

Good Luck!

Mitechniq

if you can memorize 128 192 224 240 248 252 254 and multiple's of 16 ( I say 16's because I find it the hardest one to memorize).. it really doesn't get any more complicated than that...

For example "Enter the first valid host on the network that the host 172.25.188.168 255.255.240.0"

256 - 240 is 16, so counting by 16's you get to 176 without going over the .188 which makes

172.25.176.0 Network
172.25.176.1 First Host
172.25.191.254 Last Host
172.25.191.255 Broadcast
172.25.192.0 Would be the Next Network

Binary Freak

Try this

-Binary Freak

ccnxjr

Ah, yes, the elusive Binary Math "shortcut" .
The 'best' method may vary from person to person.
However all methods share at least this in common, you still need lots of practice.
*something something about young people today*

xnx

auxiliarypriest wrote: »

I finger subnet too! But I definitely agree with ninjaturtle and learn the long way to understand what you are doing first. The tricks will help with speed. Danscourses did a subnet tutorial it might help you out...Subnetting, Cisco CCNA, Binary Numbers -Part 1 - YouTube

This is my technique too

[Deleted User]

Can anyone explain VLSM? This is a topic that is difficult to understand. I understand subnetting but not this topic.

jem7sk

Might be the best $1 you ever spend:
http://www.amazon.com/gp/product/B00G6L06VU/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B00G6L06VU&linkCode=as2&tag=thebryaadva06-20&linkId=EKQ2RJVL2MVXVV2Q

colemic

IP Subnetting Made Easy: John J Kowalski: 9781615391745: Amazon.com: Books

No one way/explanation of subnetting works for everyone, but this book vastly simplified it for me...

chopsticks

I finally "got it" after reading repeatedly Mr Odom Wendell's CCENT/CCNA Study Guide Book, I highly recommend it.

sno

There is a lot of subnetting guides out there. Find one that sort of makes sense, and then try to impliment it. You wont really be able to understand subnetting from simply reading a how-to. You need to actually practice subnetting. Do so, either in a home lab or on a subnetting practice website. Some people do binary math in their head, others use powers of two. Find a way that works for you by trying to few different ways of doing things.

Sirah8499

Wendell Odom has an EXCELLENT subnetting process. I highly recommend it. Though once you grasp the concept you can eliminate a lot of the steps he makes you follow.

Tips for subnetting:
1. Memorize the powers of 2 up to the 16th power so that you can determine the hosts or subnets needed.
2. Memorize the values that you get in the subnet mask when you borrow bits. For example, if you are using a /27 prefix, 27-24=3. With 3 leftover bits you would have the last octet with a value of 224 because 3 bits in binary is:

128 64 32 16 8 4 2 1

1 1 1 0 0 0 0 0

so 128+64+32=224

The reason I subtracted 27-24 is because 8 can go into 27 3 times, so you have 3 octets with a value of 255 when using a prefix of /24. In the end the subnet mask is 255.255.255.224

You can find the range of subnets by subtracting the last octet value from 256. So 256-224=32. This means that the range of subnets would be:

0, 32, 64, 96, 128, 160, 192

If you pick the 32-63 range. This is what the numbers mean:
-The first number (32 in this case) is the Network ID.
-The second number (33) is the first usable host
-The last usable host is 62
-The broadcast address is 63

Sirah8499

kMastaFlash wrote: »

Can anyone explain VLSM? This is a topic that is difficult to understand. I understand subnetting but not this topic.

If you can subnet you can VLSM. Start with the largest subnet (the smallest prefix) and get the hosts you need. Then increase the prefix to accommodate the next subnet requirements using the next following subnet as the starting point.

ImYourOnlyDJ

kMastaFlash wrote: »

Can anyone explain VLSM? This is a topic that is difficult to understand. I understand subnetting but not this topic.

VLSM can be hard to comprehend at first, but easy once you get it. It's basically like subnetting an already subnetted network. For example if you need a subnet with 60 hosts and two subnets with 2 hosts from 192.168.1.0 /24 you could create a /26 subnet mask with a range from 192.168.1.0 - 192.168.0.63. Then have another subnet with a /30 mask with a range from 192.168.0.64 - 192.168.0.67 and another with the same mask from 192.168.0.68 - 192.168.0.71.

Hope I didn't confuse you

markulous

ImYourOnlyDJ wrote: »

VLSM can be hard to comprehend at first, but easy once you get it. It's basically like subnetting an already subnetted network. For example if you need a subnet with 60 hosts and two subnets with 2 hosts from 192.168.1.0 /24 you could create a /26 subnet mask with a range from 192.168.1.0 - 192.168.0.63. Then have another subnet with a /30 mask with a range from 192.168.0.64 - 192.168.0.67 and another with the same mask from 192.168.0.68 - 192.168.0.71.

Hope I didn't confuse you

Just to piggyback on this, you don't need to worry about whether or not the next set of numbers is divisible by the next bit increment or not since any number you use is going to evenly go into whatever number your starting with.

In the above example, you were using increments of 64, so the next increment you use will be either 32, 16, 8, 4, or 2, so all of those will work with that just fine.

Not sure I explained that well.