IP Range

Discussion in 'Site & Server Administration' started by black.hat, Sep 17, 2010.

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  1. #1
    How many usable ip a /21 range have?
     
    black.hat, Sep 17, 2010 IP
  2. RonBrown

    RonBrown Well-Known Member

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    #2
    4078 (with 1 broadcast and 1 subnet) but you'd never use a continuous range that size It would usually be split into different VLANs and subnets so the true answer is some figure between 2040 and 4078, and if you're using redundant switches on a subnet then somewhere between 1020 and 4078. Should be enough to get started with.
     
    RonBrown, Sep 17, 2010 IP
  3. secureax

    secureax Member

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    #3
    Here you go.
     
    secureax, Sep 17, 2010 IP
  4. Mohie

    Mohie Peon

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    #4
    Subnet mask /21 means: 255.255.248.0

    XXXXXXXX.XXXXXXXX.XXXXXYYY.YYYYYYYY

    All the Y's are the one for the hosts, each one can take one of two values: 0 or 1.

    means : 2^11 = 2048

    but u need to remove 2 ips , one for broadcast and one for subnet mask

    so 2048 - 2 = 2046 ips.

    TOTAL Number of ips usable for /21 subnet is 2046 ips


    Regards,
    Mohie.
     
    Mohie, Sep 17, 2010 IP
  5. RonBrown

    RonBrown Well-Known Member

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    #5
    Yep, my kistake. Can't count properly when it becomes binary.
     
    RonBrown, Sep 18, 2010 IP
  6. Mia

    Mia R.I.P. STEVE JOBS

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    #6
    This might help!
    __________________________________________________________
    Netmask Netmask (binary) CIDR Notes
    __________________________________________________________
    255.255.255.255 11111111.11111111.11111111.11111111     /32     Host
    (single address)
     
    255.255.255.254 11111111.11111111.11111111.11111110     /31     Unuseable
    255.255.255.252 11111111.11111111.11111111.11111100     /30     2   useable
    255.255.255.248 11111111.11111111.11111111.11111000     /29     6   useable
    255.255.255.240 11111111.11111111.11111111.11110000     /28     14  useable
    255.255.255.224 11111111.11111111.11111111.11100000     /27     30  useable
    255.255.255.192 11111111.11111111.11111111.11000000     /26     62  useable
    255.255.255.128 11111111.11111111.11111111.10000000     /25     126 useable
    255.255.255.0     11111111.11111111.11111111.00000000     /24     "Class C"
    254 useable
     
    255.255.254.0   11111111.11111111.11111110.00000000     /23
    255.255.252.0   11111111.11111111.11111100.00000000     /22
    255.255.248.0   11111111.11111111.11111000.00000000     /21
    255.255.240.0   11111111.11111111.11110000.00000000     /20
    255.255.224.0   11111111.11111111.11100000.00000000     /19
    255.255.192.0   11111111.11111111.11000000.00000000     /18
    255.255.128.0   11111111.11111111.10000000.00000000     /17
    255.255.0.0       11111111.11111111.00000000.00000000     /16     "Class B"
     
    255.254.0.0     11111111.11111110.00000000.00000000     /15
    255.252.0.0     11111111.11111100.00000000.00000000     /14
    255.248.0.0     11111111.11111000.00000000.00000000     /13
    255.240.0.0     11111111.11110000.00000000.00000000     /12
    255.224.0.0     11111111.11100000.00000000.00000000     /11
    255.192.0.0     11111111.11000000.00000000.00000000     /10
    255.128.0.0     11111111.10000000.00000000.00000000     /9
    255.0.0.0         11111111.00000000.00000000.00000000     /8      "Class A"
     
    254.0.0.0       11111110.00000000.00000000.00000000     /7
    252.0.0.0       11111100.00000000.00000000.00000000     /6
    248.0.0.0       11111000.00000000.00000000.00000000     /5
    240.0.0.0       11110000.00000000.00000000.00000000     /4
    224.0.0.0       11100000.00000000.00000000.00000000     /3
    192.0.0.0       11000000.00000000.00000000.00000000     /2     64 A's
    128.0.0.0       10000000.00000000.00000000.00000000     /1     128 A's
    0.0.0.0           00000000.00000000.00000000.00000000     /0      IP Space
     
    Mia, Sep 24, 2010 IP