Subnetting?

KDEKDE ■□□□□□□□□□ Posts: 20Member ■□□□□□□□□□
Does anybody know of a good site that explains how to figure out and use subnetting? I looked in the technotes, but wasn't able to find anything other than the subnet masks for Class A-C IP addresses.

255.0.0.0 - A
255.255.0.0 - B
255.255.255.0 - C

I know the purpose of it, but I don't understand how the formula is used to get the subnets and what range of Ip addresses would be valid in that subnet.


Thanks,
Cliff
knowledge is power!
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Comments

  • WebmasterWebmaster Admin Posts: 10,292Admin Admin
    There's nothing about subnetting in the TechNotes because subnetting is not a topic in the Net+ exam...

    "subnetting" refers to stealing bits from the host portion to allow class A, B and C networks to be divided in several "subnets". For the network+ exam you don't need to know how to actually calculate the amount of hosts or subnet, the broadcast address, (sub)network address, and the actually IP address ranges given a subnet mask, or ip address and subnet mask. This is a essential topic of the CCNA exam though...

    Nevertheless: www.learntosubnet.com
  • KDEKDE ■□□□□□□□□□ Posts: 20Member ■□□□□□□□□□
    thanks for the link!
    knowledge is power!
  • carbunklecarbunkle ■■□□□□□□□□ Posts: 97Member ■■□□□□□□□□
    I remeber my teacher in high school making it really complicated but isnt it just a matter of setting the available octets to the highest number available? So a class C network is A.B.C.0 and a regular subnet mask would be 255.255.255.0. To split the network in two you would set the subnet mask to the top of the first half so 255.255.255.127 and the addresses would be anything A.B.C.1 - A.B.C.126. let me know if I am wrong.
  • KingKKingK ■■□□□□□□□□ Posts: 35Member ■■□□□□□□□□
    We did so much subnetting in the Cisco Phaze of my class, its almost second nature to me.

    Of the 10 week phaze, the first 4 weeks was NOTHING but subnetting and figuring static routes.

    CIDR's make it a bit easier.

    Everyday for 4 weeks, homework and everything.

    Some people STILL didnt get it.
  • mynameisboringmynameisboring ■■□□□□□□□□ Posts: 75Member ■■□□□□□□□□
    I've seen experienced people have to put in some thought for subnetting, but with that said its not that hard. If you practice it you get it.

    Personally I like to convert the octets into binary and work from there so
    255.255.255.0 would be 1111 1111.1111 1111.1111 1111.0000 0000 and to create the subnet I'd change the binary code to something like 1111 1111.1111 1111.1111 1111.1111 0000 or 255.255.255.240.

    Why? BECAUSE BINARY IS KING!
  • KingKKingK ■■□□□□□□□□ Posts: 35Member ■■□□□□□□□□
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