Is this a correct subnet?

[imported_dareino]

My ISP is giving me 24.4.232.xxx IP address but I noticed I have a 255.255.255.0 subnet? Is that right? I thought a 24. would be considered a Class A Address and the subnet would be 255.0.0.0?
Been awhile since I took a networking class

 

[jlazzaro]

nowadays, we arent bound by classes...reference CIDR.

 

[dfnkt]

no its fine, that means they are giving 256* 'usable' addresses, so your range is 24.4.232.0 to 24.4.232.255 however you cant use .0 or .255 (net id/multicast ip)

and what jlazzaro is talking about is Classless Interdomain Routing (CIDR)

http://en.wikipedia.org/wiki/C...s_Inter-Domain_Routing

Its subnetting reversed..kind of, sometimes referred to as supernetting. Basically in CIDR notation instead of writing 255.255.255.0 all day long, its just /24. The slash 24 is used because that referes to the 8bits in each octet of the subnet mask. Since all 8 bits are "on" in 255, and you have 3 "255"s then 8 times 3= 24, thus /24.

If you dont understand the 8 bits thing, here you go

128 64 32 16 8 4 2 1 those are the values for it (or 11111111 if you want binary) and all those numbers added together equals 255 🙂

 

[jlazzaro]

Originally posted by: dfnkt
no its fine, that means they are giving 256* 'usable' addresses, so your range is 24.4.232.0 to 24.4.232.255 however you cant use .0 or .255 (net id/multicast ip)

that isnt what it means at all...just because he has a /24 doesnt mean that entire range is usable by him.

 

[dfnkt]

On a private network, nothing should prevent him from using all 255 address, unless you have one hell of a stingy ISP if that were the case, why not give him /32

 

[spidey07]

Because there is no such thing as a /32. OP is most likely using cable and a ip network or subnet is bounded by the broadcast domain.

If they started handing out /30s then half of their address space is wasted.

 

[dfnkt]

stinks=/ yeah i dont see them wasting address space

 

[dfnkt]

Anyway, as you see above part of my information is incorrect, however I have a /24 and have access to all of the ips in that range.

 

[jonmcc33]

Originally posted by: dareino
My ISP is giving me 24.4.232.xxx IP address but I noticed I have a 255.255.255.0 subnet? Is that right? I thought a 24. would be considered a Class A Address and the subnet would be 255.0.0.0?
Been awhile since I took a networking class

You need serious lessons in subnetting it seems. Take something more advanced. Cisco's Network Academy is quite good if your instructor has a clue.