Subnetting question

You will need a good understanding of binary to completely comprehend subnetting.

http://www.semsim.com/ccna/tutorial/subnetting/subnetting.html
http://www.osix.net/modules/article/?id=422

Oh, and of course, a TR article: http://articles.techrepublic.com.com/5100-1035-6089187.html

You should know that the maximum value per octet is 255 so you go octet by octet and take the difference between the 2 values and substract that from 255:

First octet = 207 and 207, diff = 0 so mask value = 255 - 0 = 255
Second octet = 46 and 46, diff = 0 so mask value = 255 - 0 = 255
Third octet = 200 and 207, diff = 7 so mask value = 255 - 7 = 248
Fourth octet = 0 and 255, diff = 255 so mask value = 255 - 255 = 0

Which gives you a mask of 255.255.248.0

(Of course since bits have to be contiguous in a subnet mask once you find a non-255 value you don't have to calculate the remaining octet(s) as everything that follows has to be 0)

u give the ip range from 207.46.200.0 to 207.46.207.255
first understand that it as a class C ip address
find out the changes b/w 2 ip address
A.B.C.D ie A=207 B=46 C=200 to 207 & D=0 to 255
first changes started from c (200 to 207)
therefore subnet mask is 255.255._.0 for A&B
for c there is 8 is the difference(256-248=8 OR 256-8=248)
there for by adding the 248 for C we get
255.255.248.0