subnet mask quick question

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  EdTheLad Member Posts: 2,111 ■■■■□□□□□□

  May 2005

  Karimbruxelles wrote:

  Hi Guys,
  
  On Class C adress, borowing 3 bits for the subnet mask e.g 255.255.255.224
  Can I assign host address starting from 1,2,3 etc... or shall I start to assign adress from 32?
  
  e.g
  
  200.1.1.2
  255.255.255.224
  
  OR
  
  I can only start from
  
  200.1.1.33
  255.255.255.224
  
  
  Please help as now I'm really confus
  
  
  Thanks

  
  This all depends if IP Subnet-Zero is enabled on your cisco router or not.
  In early releases on cisco IOS subnet-zero was switched off by default meaning the first and the last subnet were not used.
  So your above answer 200.1.1.33 255.255.255.224 would be correct.
  Now cisco enables subnet-zero by default which means the first and last subnet are counted so your above answer 200.1.1.1 255.255.255.224 would be correct.
  In the exam do not include subnet-zero if you are not explicitly told it is enabled.Now with reference to other ip vendor equipment like Riverstone,Alcatel,Redback blah blah blah they dont have the concept of subnet-zero and recognise all subnets by default.
  Hope this helps,but if you read the forum you will see this has been discussed before!!!

  Networking, sometimes i love it, mostly i hate it.Its all about the $$$$

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  Karimbruxelles Users Awaiting Email Confirmation Posts: 7 ■□□□□□□□□□

  May 2005

  Thanks a lot for your quick answer
  
  Cheers
  
  Karimbruxelles

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  Karimbruxelles Users Awaiting Email Confirmation Posts: 7 ■□□□□□□□□□

  May 2005

  But My 1st Hosts adress should start at 33 or ?
  e.g 200.1.1.33 255.255.255.224
  
  subnet number 200.1.1.32
  
  Because if I use 200.1.1.3 255.255.255.224 for e.g
  My subnet number will be 200.1.1.0
  
  Could you please clarify this?
  
  Thanks a lot

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  EdTheLad Member Posts: 2,111 ■■■■□□□□□□

  May 2005

  with subnet-zero
  subnets= 0,32,64,96......224
  I think you should be able to work out the hosts?
  If not read a book
  
  without subnet-zero
  subnets=32,64,96......192
  I think you should be able to work out the hosts?
  If not read a book

  Networking, sometimes i love it, mostly i hate it.Its all about the $$$$

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  Karimbruxelles Users Awaiting Email Confirmation Posts: 7 ■□□□□□□□□□

  June 2005

  OK I understand now
  
  I'm so glad, thx matte

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