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- Subject
- Posted on
- A few subnetting question
- 05-07-2007
posted on
May 7, 2007, 5:28 pm
May 7, 2007, 5:28 pm
I am working through subnetting question and I had two that I was not sure
about:
1) a firm is assigned the network part 128.171. It selects an 8-bit subnet
part. Represent the second host on the third subnet in dotted decimal
notation.
I came up with 128.171.4.2
2) You have a 20-bit network part and a 4-bit subnet part, how many hosts
can you have per subnet?
a. 14
b. 16
c. 254
d. 256
e. none of the above
I came up with C
Do these answers look right?
Thanks
about:
1) a firm is assigned the network part 128.171. It selects an 8-bit subnet
part. Represent the second host on the third subnet in dotted decimal
notation.
I came up with 128.171.4.2
2) You have a 20-bit network part and a 4-bit subnet part, how many hosts
can you have per subnet?
a. 14
b. 16
c. 254
d. 256
e. none of the above
I came up with C
Do these answers look right?
Thanks
Re: A few subnetting question
The way I figured the second problem was if you had 20 bits for the
network and 4 bits for the subnet you have 8 bits left for the hosts.
20+4+8=32
8 bits = 256 hosts - 2 for broadcast and network = 254.
I am lost on the first question, it seems that you would need a subnet
mask to answer this question.
Thanks for looking
network and 4 bits for the subnet you have 8 bits left for the hosts.
20+4+8=32
8 bits = 256 hosts - 2 for broadcast and network = 254.
I am lost on the first question, it seems that you would need a subnet
mask to answer this question.
Thanks for looking
Re: A few subnetting question
128.171.x.x is a class B address, therefore the eight bit subnet will be in
the third octet.
So the counting the subnets up I get :-
128.171.0.0 This is the zero subnet not normally acknowledged or required on
the CCNA unless specifically asked for so I discount it (please can someone
correct me if this wrong!).
128.171.1.0 First subnet
128.171.2.0 Second subnet
128.171.3.0 Third subnet
So I get 128.171.3.2 as the second host on the third subnet.
As for question 2 I think this is more simple. It's a trick question. There
can't be a 20 bit network part for the address.
A = 8 network bits.
B = 16 network bits
C = 24 network bits.
I would therefore have to go with e for this question.
K.
I am working through subnetting question and I had two that I was not sure
about:
1) a firm is assigned the network part 128.171. It selects an 8-bit subnet
part. Represent the second host on the third subnet in dotted decimal
notation.
I came up with 128.171.4.2
2) You have a 20-bit network part and a 4-bit subnet part, how many hosts
can you have per subnet?
a. 14
b. 16
c. 254
d. 256
e. none of the above
I came up with C
Do these answers look right?
Thanks
Re: A few subnetting question
On Tue, 8 May 2007 10:03:50 +0100
The recommendation in the CCNA Cisco Press exam guide (Appendix D p592) is:
If there is no hint in the question use 2^n-2
If the Q includes the words 'classful' 'RIPv1' or is not using VLSM -> 2^n-2
If the Q includes the words 'classless' 'OSPF' 'EIGRP' 'RIPv2' or uses VLSM ->
2^n
The question may explicitly say which to use, or simply infer it.
Cisco themselves give no direct recommendation.
The recommendation in the CCNA Cisco Press exam guide (Appendix D p592) is:
If there is no hint in the question use 2^n-2
If the Q includes the words 'classful' 'RIPv1' or is not using VLSM -> 2^n-2
If the Q includes the words 'classless' 'OSPF' 'EIGRP' 'RIPv2' or uses VLSM ->
2^n
The question may explicitly say which to use, or simply infer it.
Cisco themselves give no direct recommendation.
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