I thought I had gotten a firm grasp when the underlisted through me off balance. Please kindly help with an explanation on finding the Mask.

Which Network Mask should you place on a Class C address to accommodate a user requirement of 2 sub networks with a maximum of 35 hosts on each network?
a. 255.255.255.192
b. 255.255.255.224
c. 255.255.255.240
d. 255.255.255.248

Class C default 255.255.255.0
Last octet would be determined from no. of. Hosts & Nets.
Since there are 35hosts on each net, 2 subnets then we’d apply 224 (3 subnet bits, 5zeros – since we need max. of 35hosts)
255.255.255.224. Answer seems to be A. Please tell me where I’ve gone wrong

Which Network Mask should you place on a Class C address to accommodate a user requirement of 5 networks with a maximum of 17 hosts on each network?
a. 255.255.255.192
b. 255.255.255.224
c. 255.255.255.240
d. 255.255.255.248

Same reasoning as above and I come up with answer B. 255.255.255.224
Answer this time is B
I seem to be leaving a tiny concept behind. Someone Please put me in the loop!

There’s a very controversial question about Ping operating in Transport or Network?

I feel it’s Network since ping uses ICMP (echo request & reply). ICMP operates at the Network layer. Secondly, when a host say A ping another host B, a packet is generated in Host A. Packets are basically dealt with at The Network Layer.

Please let me have your views on this.

B. IBI

quote:

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Hello guys,

I thought I had gotten a firm grasp when the underlisted through me off balance. Please kindly help with an explanation on finding the Mask.

Which Network Mask should you place on a Class C address to accommodate a user requirement of 2 sub networks with a maximum of 35 hosts on each network?
a. 255.255.255.192
b. 255.255.255.224
c. 255.255.255.240
d. 255.255.255.248

Class C default 255.255.255.0
Last octet would be determined from no. of. Hosts & Nets.
Since there are 35hosts on each net, 2 subnets then we’d apply 224 (3 subnet bits, 5zeros – since we need max. of 35hosts)
255.255.255.224. Answer seems to be A. Please tell me where I’ve gone wrong

Which Network Mask should you place on a Class C address to accommodate a user requirement of 5 networks with a maximum of 17 hosts on each network?
a. 255.255.255.192
b. 255.255.255.224
c. 255.255.255.240
d. 255.255.255.248

Same reasoning as above and I come up with answer B. 255.255.255.224
Answer this time is B
I seem to be leaving a tiny concept behind. Someone Please put me in the loop!

There’s a very controversial question about Ping operating in Transport or Network?

I feel it’s Network since ping uses ICMP (echo request & reply). ICMP operates at the Network layer. Secondly, when a host say A ping another host B, a packet is generated in Host A. Packets are basically dealt with at The Network Layer.

Please let me have your views on this.

B. IBI

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This is my little trick for their questions on subnetting.
ok for your first question they ask you for 35 usable subnets.
Always remember that u are gonna have to minus 2.
Take 255 and subract 224. your answer will be 31, then u have to minus 2 which will only leave you with 29 usable hosts. So you know that cant be the answer. then take 255 and minus 192, that will give you 63 then minus 2 and you have 61 usable hosts which will meet your req of 35 usable hosts. The same logic can be applied to your second question too.

Or you could also count out the zeros left in the subnet ex:
11111111.11111111.11111111.11000000 count the zeros and times it by the power of 2. so it would be 2,4,8,16,32,64 then minus 2 and you will also have your usable hosts. if the last octet were 224 or
11100000 the zeros only leave you with 2 to the power of 5 which is only 32 the you have ot minus two, which is 5 less than 35.

Edited by - jumper5 on Jul 21 2002 1:11:55 PM