a basic subnetting question

Discussion in 'Networks' started by kobem, Sep 29, 2007.

  1. kobem

    kobem Megabyte Poster

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    so with one 192.168.0.0 is used just for network 1 or network 2 or network 3 ?
     
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  2. JonnyMX

    JonnyMX Petabyte Poster

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    Oh for f**k's sake.

    See Ben.
    See Ben's ball.
    See Ben's blue ball.

    Run, Ben, run.

    Catch the ball, Ben!

    When you grow up, you can do subnetting!

    :rolleyes:
     
    Certifications: MCT, MCTS, i-Net+, CIW CI, Prince2, MSP, MCSD
  3. GiddyG

    GiddyG Terabyte Poster Gold Member

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    Umm... OK, so is 192.168. Class B or Class C?

    Or did you miss my question? :twisted:
     
  4. stuPeas

    stuPeas Megabyte Poster

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    Its B
     
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  5. JonnyMX

    JonnyMX Petabyte Poster

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    Wasn't aimed at you, mate.

    I think the answer to the question is 'a small town outside Basingstoke with a type 2 BT exchange box'.

    If that helps.
     
    Certifications: MCT, MCTS, i-Net+, CIW CI, Prince2, MSP, MCSD
  6. GiddyG

    GiddyG Terabyte Poster Gold Member

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    Lawl... I knew it wasn't, and maybe I shouldn't ask why 192.168 could be Class B. I am confused enough as it is re subnetting. :eek:
     
  7. MacAllan

    MacAllan Byte Poster

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    No, it's C

    I suggest you look at it in binary.

    Class A begins 0
    Class B begins 10
    Class C begins 110
    Class D begins 1110 .....

    In any event, class for networks is largely irrelevant these days outside cert exams - google CIDR.
     
    Certifications: A+, N+, CCNA
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  8. stuPeas

    stuPeas Megabyte Poster

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    My mistake. Its been a while!!
     
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  9. GiddyG

    GiddyG Terabyte Poster Gold Member

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    Thank gawd for that! Lawl... :D

    Cheers guys.
     
  10. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    Hmm..

    192.168.0.0 is the allocated network address.

    Kobem could use..

    192.168.1.0 for one segment

    192.168.2.0 for another

    and

    192.168.3.0 for the remaining one.

    These are class C IP addresses.

    But if you use a class B subnet mask of 255.255.0.0 problem solved.

    this would work, without any actual subnetting ie stealing host bits to create subnets.

    That is how i would answer the question and then run for the door :)
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  11. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Er - <cough> - the book is out of date. Classes have gone in the Internet at large, we now have CIDR (Classless Internet Domain Routing). Classs are only retained for 'legacy' stuff.

    Having said that - you need to have both old and new on board. You will find that many exams, (not just N+ but Cisco as well) will ask about classes.

    Harry.
     
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  12. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Neither - it is a /16 network.

    Harry.
     
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  13. dmarsh
    Honorary Member 500 Likes Award

    dmarsh Petabyte Poster

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    Well i'm no expert but wouldn't

    Mean you had created three networks by subnetting which is not an allowed option ?

    Also using a different subnet mask would in effect make it not class C but CIDR as harry says.

    This would in fact steal network bits for clients as you've taken one octet from the network and given it to the client portion.

    As with most of kobems questions I can't make any sense of it, like people have said either its one network or its two. Two networks require two network addresses. Thoose addresses could be 192.168.1.0,
    or 192.168.2.0 or anthing in the valid range defined by the subnet mask and the TCP/IP standards private addresses. As far as I know you always need a mask to make use of an IP address, so maybe the question should be without using a 'custom' subnet mask.
     
  14. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    Yes this was my point ^^

    Cisco refer to 255.255.0.0 as a *natural mask* anything that isn't a 255 octet is refered to as subnetting.

    the whole story

    So, in answer to this..

    No :)

    Whatever, it's not relevant to whether it would work or not these are purely terms, which have evolved over time. I am not disputing what Harry says and sure CIDR VLSM etc are used more nowadays but to grasp the basics, i dont think it helps Kobem by clouding the issue.
     
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  15. ffreeloader

    ffreeloader Terabyte Poster

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    Yup. You're correct. My only excuse is that I must have been having some kind of major brain fart to say what I did. :biggrin
     
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  16. tripwire45
    Honorary Member

    tripwire45 Zettabyte Poster

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    I hope that kobem is getting something out of this thread and it seems like he's inadvertantly spawned a pretty good subnetting discussion for the rest of us. :wink:
     
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  17. MacAllan

    MacAllan Byte Poster

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    If you use a mask of 255.255.0.0, then you only have one network, not three, as the mask is saying that the network part of any address is in the first two octects and anything in the third or fourth octect is a host address.

    If you used a 255.255.255.0 mask with the three network addresses you have designated, then yes, you have three networks, without subnetting, and Kobem's problem is solved.

    I suspect he is misunderstanding a question he has seen, on a bdump, I would guess, which he is re-wording to cover up the fact, but which he can't post the original of or we would know, and can't word properly because he has such an appalling grasp of the fundamentals. Am I being unfair? Well look at his first posts here, and a little googling will show his similar activity on other fora.

    Of course, he can always post the original, as he has been asked to, and if I'm wrong I'll apologise....
     
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  18. MacAllan

    MacAllan Byte Poster

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    Like I posted, beginning 10 is class B, beginning 110 is class C

    In CIDR what is important is the subnet mask:

    192.168.0.0 with a 255.255.255.0 is a /24
    192.168.0.0 with a 255.255.0.0 is a /16 ( = supernetting)
    192.168.0.0 with a 255.0.0.0 is a /8 ( = supernetting)
    192.168.0.0 with a 255.255.255.252 is a /30 ( = subnetting)

    The number after the slash is the count of binary digits that make up the mask, that is, are the network portion of the address.

    But some software will not accept these types of masks, while others will, so unless you are sure of everything that will interact with your system, while it's usually okay to subnet, to use supernetting is more of a risk.

    So here's a question for all you N+ students:

    192.168.0.0 with a 255.255.255.128 is a /25

    Is it valid?
     
    Certifications: A+, N+, CCNA
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  19. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    Yes you are correct my bad :)
     
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  20. ffreeloader

    ffreeloader Terabyte Poster

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    Yeah, you could do that. Along those same lines you could also go with a 255.255.252.0 and have a usable subnet mask for which you would have 64 network blocks with 4 /24 (Class C) network address blocks per subnet(192.168.0.0 - 192.168.3.255, 192.168.4.0 - 192.168.7.255, etc...). That is, it will work if the router will accept a 0 address as a valid network address.
     
    Certifications: MCSE, MCDBA, CCNA, A+
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