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May 3, 2007, 10:37 pm

The problem:
You have a IP of 202.99.212.0
You need 4 Subnets
I say Mask with 255.255.255.192
I say there will be 62 hosts per subnet
Nets are:
202.99.212.0
202.99.212.64
202.99.212.128
202.99.212.192
Am I correct?
http://www.gt-solutions.com/cgi-bin/subnet-1.cgi said I was wrong...and
they give the answer as:
Mask 255.255.255.224
With first host in the next net as 202.99.212.33
Which one of us is wrong? To me this says 8 subnets with 30 hosts per
subnet.
Brian
You have a IP of 202.99.212.0
You need 4 Subnets
I say Mask with 255.255.255.192
I say there will be 62 hosts per subnet
Nets are:
202.99.212.0
202.99.212.64
202.99.212.128
202.99.212.192
Am I correct?
http://www.gt-solutions.com/cgi-bin/subnet-1.cgi said I was wrong...and
they give the answer as:
Mask 255.255.255.224
With first host in the next net as 202.99.212.33
Which one of us is wrong? To me this says 8 subnets with 30 hosts per
subnet.
Brian

Re: Check my subnetting?

Brian,
They are probably excluding all 0's and 1's, i.e. the first and last
subnets. Lookup "subnet zero". This might help, see
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080093f18.shtml
--
Ray

Re: Check my subnetting?
On Thu, 03 May 2007 22:37:43 GMT

Their quiz is for people who are studying MCSE-type exams as well as cisco.
With Microsoft exams, all-zero and all-1 subnets are not counted. Look down the
page, it says that they aren't for the purposes of this quiz.
By their rules, they are right and you are wrong. As with any exam, it's the
exam answer that is correct ;-)

Their quiz is for people who are studying MCSE-type exams as well as cisco.
With Microsoft exams, all-zero and all-1 subnets are not counted. Look down the
page, it says that they aren't for the purposes of this quiz.
By their rules, they are right and you are wrong. As with any exam, it's the
exam answer that is correct ;-)

Re: Check my subnetting?
On 5 May 2007 08:01:18 -0700

CCNA may have questions that require use of subnet-zero (and all-1s subnet) and
questions that do not. The hint is always meant to be there: they'll either say
right out, or infer it by reference to e.g. using RIP as the routing protocol,
VLSM or use of the words classful or classless in the question.
On the web-site the OP is using, it specifically says not to use subnet zero to
answer the quiz - how specific do you want?
Like I said before, in an exam you are trying to see what answer the examiner
is looking for, and the examiner is always right (even when they're wrong!).

CCNA may have questions that require use of subnet-zero (and all-1s subnet) and
questions that do not. The hint is always meant to be there: they'll either say
right out, or infer it by reference to e.g. using RIP as the routing protocol,
VLSM or use of the words classful or classless in the question.
On the web-site the OP is using, it specifically says not to use subnet zero to
answer the quiz - how specific do you want?
Like I said before, in an exam you are trying to see what answer the examiner
is looking for, and the examiner is always right (even when they're wrong!).

Re: Check my subnetting?

Hi. Yes - I've been trying to dig it up in a couple of study books but no
luck with a definitive quote yet. The rule of thumb I think (again I use the
term allegedly) is that if the phrase 'zero subnet' is not present in the
question then you have to disregard the first and last subnets. If it is,
you must count them all.
ACL's are similar in that you can use that 'resequence' command from V12.4
onward, but that's not how the test treats it. As Brad Reese said in an
earlier quote :"think in terms of doing it the 'Cisco Way'". Sagely advice.
PM

Re: Check my subnetting?

Many thanks-can you enlighten me on the resequence you mention for
ACLs please? I am not aware of this-is it the implicit deny any at the
end of the ACL?
To digress slightly I am assuming hosts are classed as usable unless
otherwise stated? for example .224 would be 30 usable 32 possible.

Re: Check my subnetting?
That link has taught me more about subnetting than anything else I have
tried. I am very confident in my subnetting capabilities now.
Rule of thumb...if they say no zero nets and ask for subnetting to make 4,
8, 16, 32, 64, 128, 256 networks etc you better add two.
So if they want 4 nets, with no zero nets, then you need to figure for 6..so
you need to borrow three bits for subnetting.
192.168.1.0/27
192.168.1.32/27
192.168.1.64/27
192.168.1.96/27
192.168.1.128/27
192.168.1.160/27
192.168.1.192/27
192.168.1.224/27
If the rule is no zero subnets, and you only use two borrowed bits you get:
192.168.1.0/26
192.168.1.64/26
192168.1.128/26
192.168.1.192/26
Which IS 4 subnets, but the first one doesn't count because this is a no
zero subnet question.
SO...my lesson learned is to READ every word of the question twice, and
don't assume a damn thing.

tried. I am very confident in my subnetting capabilities now.
Rule of thumb...if they say no zero nets and ask for subnetting to make 4,
8, 16, 32, 64, 128, 256 networks etc you better add two.
So if they want 4 nets, with no zero nets, then you need to figure for 6..so
you need to borrow three bits for subnetting.
192.168.1.0/27
192.168.1.32/27
192.168.1.64/27
192.168.1.96/27
192.168.1.128/27
192.168.1.160/27
192.168.1.192/27
192.168.1.224/27
If the rule is no zero subnets, and you only use two borrowed bits you get:
192.168.1.0/26
192.168.1.64/26
192168.1.128/26
192.168.1.192/26
Which IS 4 subnets, but the first one doesn't count because this is a no
zero subnet question.
SO...my lesson learned is to READ every word of the question twice, and
don't assume a damn thing.

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