Subnetting in 5 seconds

samritz

after reading these methods i thought there were pretty cool. check it out and see if maybe i got something wrong somewhere.


1. what subnet mask to use?

any question askng for what subnet mas to use in a given scenario, e.g
XYZ Corporation is using the 192.168.100.0 private address to implement a workgroups in their network. Each workgroup will consist of 17 devices requiring IP addresses. One additional address is required for the router
interface in each subnet. What subnet mask should XYZ use?

first-determine number of addresses n this case 18
next-next round to the next power of 2 , this case next power f 2 after 18 is 32.
Subtract 32 from 256 you get 224.
its a class c so its in the forth octect i.e 255.255.255.224.
that'll be the subnet mask required.

works well with class C.

In class B,

XYZ Corporation is using 172.16.0.0 for their networking needs. Each subnet requires 280 IP addresses including
the router interface. What subnet mask should be used?

Where the numebr of addresses is greater than 256, divide the number of addresses by 256, in this case 280/256 =1 remainder something(forget the rmainder).If there is a remander, add one to the quotient, that is 1 in this case, we have 2. As we did b4 subtract 2 frm 256 and u get 254. that in in the 3rd octect.
so the mask is 255.255.254. simple huh?

whe i first read it, it was boring, then i just was going throu it by chance and it struct me, only addition, multiplication and subtraction, with low numbers, its really fast when u practice say about ten subnetting questions with this.

Try it. I'm glad i tried it, cuz i was having problem wiht the time issue on these subnetting questions.

Handbrake

samritz wrote: »

after reading these methods i thought there were pretty cool. check it out and see if maybe i got something wrong somewhere.


In class B,

XYZ Corporation is using 172.16.0.0 for their networking needs. Each subnet requires 280 IP addresses including
the router interface. What subnet mask should be used?

Where the numebr of addresses is greater than 256, divide the number of addresses by 256, in this case 280/256 =1 remainder something(forget the rmainder).If there is a remander, add one to the quotient, that is 1 in this case, we have 2. As we did b4 subtract 2 frm 256 and u get 254. that in in the 3rd octect.
so the mask is 255.255.254. simple huh?

Hey! thanks for posting this seems quick!

Sorry I don't understand B

280/256 = 1.09375 = 1?
Add one to the quotient? what is a quotient in this case?
Where does the other 1 came from to sum to = 2?

Is it one from third octect and another one from fourth octect? = 2?