Hi Keith, 

If I recall correctly, the /24 part of 192.168.0.0/24 is the subnet specified 
in CIDR notation (Classless Inter Domain Routing). 

Think in binary terms, that /24 equals 11111111.11111111.11111111.00000000  
(note there's 24 1's) equals 255.255.255.0 so is a class C subnet with the 
first three octets being the network mask. 

Likewise if you had an IP addy followed by a /8 that equals 
11111111.00000000.00000000.00000000 equals 255.0.0.0 so is a class A subnet. 

Called octets cuz there's 8 bits hence a decimal max of 255.

CIDR is usually seen at ISP's or in enterprise networks that need to subnet 
further as the network mask does not have to align with the octet boundary as 
it does in the classfull network addressing we're used to. That's where things 
get weird and all this because those silly routers only speak binary. :]

If you're seeing 192.168.0.0/24 in a zenmap target field it means scan 
everything from and including 192.168.0.0 to 192.168.0.255. 


IP network classes or Classfull Network Addressing

        - Range -                                               - mask -        
        # of networks   # of nodes      CIDR mask
A       1.1.1.1 -       126.255.255.255         255.0.0.0               126     
                        16,777,214      /8
B       128.0.0.1 - 191.255.255.255             255.255.0.0             16,384  
                65,534          /16
C       192.0.0.1 - 223.255.255.255             255.255.255.0   2,097,151       
        254                     /24
D       224.0.0.1 - 239.255.255.255     
E       240.0.0.1 - 255.255.255.255



--Kenn

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