Easy Question, newbie...
M_Boyd
Member Posts: 31 ■■□□□□□□□□
in CCNA & CCENT
Hey everyone
I started a class in CCNA a week ago - on one of the first modules quiz using a subnet mask of 255.255.255.240
Now converting into binary 240
128 64 32 16 8 4 2 1
1 1 1 1 0 0 0 0
240-128=112-64=48-32=16-16=0
= 11110000
The amount left is 1+2+4+8 = 15
Now the question asked how many usable class C networks are created with this mask....
The answer is 14 - now why is that ????
I started a class in CCNA a week ago - on one of the first modules quiz using a subnet mask of 255.255.255.240
Now converting into binary 240
128 64 32 16 8 4 2 1
1 1 1 1 0 0 0 0
240-128=112-64=48-32=16-16=0
= 11110000
The amount left is 1+2+4+8 = 15
Now the question asked how many usable class C networks are created with this mask....
The answer is 14 - now why is that ????
Comments
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Webmaster
Admin Posts: 10,292 Admin
4 bits allow for 16 different values (including the zero) minus the two according to traditional subnetting (no cidr, no ip subnet-zero)= 14 usable network addresses. -
M_Boyd
Member Posts: 31 ■■□□□□□□□□
its ok found a big tutorial on it and found my answers (and then some)