When refering to IP addresses, what does /16, /32 etc. mean?

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  • Tempest
    Too lazy to set a custom title
    • May 2004
    • 10217
    #1

    When refering to IP addresses, what does /16, /32 etc. mean?

    Often times you'll some address spaces defined as 100.100.100.100/16 etc... so what does that /16 /32, /64 etc. mean? i.e. what address space does that define?
    Tags: None
    • darling2
      Confirmed User
      • Jul 2006
      • 345
      #2
      these numbers mean how many bits of the IP address you want to keep in the IP address range.

      example
      123.45.0.0/16 means all ip addresses from 123.45.0.0 to 123.45.255.255
      123.45.67.0/24 means all ip addresses from 123.45.67.0 to 123.45.67.255
      123.45.67.89/32 means just this IP address.

        Comment

        • DutchTeenCash
          I like Dutch Girls
          • Feb 2003
          • 21684
          #3
          yup

          thats how dailercompanies give access to certain server in their htaccess, range 0-16 for instance

          ICQ 16 91 547 - SKYPE dutchteencash
          bob AT dutchteencash DOT com
          ... did you see our newest Sweet Natural Girl Priscilla (18)?

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            • BoobyDuty
              Confirmed User
              • Oct 2006
              • 186
              #4
              i know i didn't ask for this info but i can certainly say thanks! i was wondering the same thing myself!
              BoobyDuty // webmaster [at] boobyduty.com // ICQ: 441-081-540

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                • Validus
                  Confirmed User
                  • Jul 2001
                  • 4012
                  #5
                  Good info for sure! Thanks!

                    Comment

                    • Tempest
                      Too lazy to set a custom title
                      • May 2004
                      • 10217
                      #6
                      Originally posted by darling2
                      these numbers mean how many bits of the IP address you want to keep in the IP address range.

                      example
                      123.45.0.0/16 means all ip addresses from 123.45.0.0 to 123.45.255.255
                      123.45.67.0/24 means all ip addresses from 123.45.67.0 to 123.45.67.255
                      123.45.67.89/32 means just this IP address.
                      Interesting... So if I had an adress defined like this:

                      123.45.67.128/28

                      That would mean 16 addresses from 123.45.67.128 to 123.45.67.143??

                        Comment

                        • Tempest
                          Too lazy to set a custom title
                          • May 2004
                          • 10217
                          #7
                          Bump....

                            Comment

                            • riddler
                              Confirmed User
                              • Oct 2004
                              • 3726
                              #8
                              Originally posted by Tempest
                              Interesting... So if I had an adress defined like this:

                              123.45.67.128/28

                              That would mean 16 addresses from 123.45.67.128 to 123.45.67.143??
                              i think so
                              Last edited by riddler; 02-07-2007, 03:36 PM.

                                Comment

                                • x-zoom
                                  Confirmed User
                                  • Jan 2007
                                  • 398
                                  #9
                                  You might want to take a look here: http://www.ralphb.net/IPSubnet/class_a.html
                                  A /28 is indeed 16 addresses in total; 14 usable with 1 network and 1 broadcast address.

                                    Comment

                                    • rowan
                                      Too lazy to set a custom title
                                      • Mar 2002
                                      • 17393
                                      #10
                                      Originally posted by x-zoom
                                      You might want to take a look here: http://www.ralphb.net/IPSubnet/class_a.html
                                      A /28 is indeed 16 addresses in total; 14 usable with 1 network and 1 broadcast address.
                                      Unless you're using a funky ethernet switch that pretends to be on a /24 subnet so you can use IPs that would have been reserved for network and broadcast

                                        Comment

                                        • madawgz
                                          8.8.8.8
                                          • Mar 2006
                                          • 30509
                                          #11
                                          thats cool, i didnt know that
                                          TAEMDLRMSKRJIXMRLSMRJ.

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