networking - Class D ip address

Is there mask for class D ip address? As it is for multicast, I am not sure about it. I read somewhere that D ip addressas are 32-bit network addresses and they dont have hostID, but in the following link I read that the number of bits for network and host is undefined in the class D. I am a little confuse a bout it, would you please guide me?

http://en.wikipedia.org/wiki/Classful_network

Answer

First classful addressing isn't used anymore, it's classless now.

Class D like any other Classes, all IPv4 addresses , are 32-bit.

Now, Judging by this link.. http://www.tcpipguide.com/free/t_IPMulticastAddressing.htm

it doesn't have network and host bits. If it's a multi-cast address then one IP would go to multiple machines anyway 'cos they'd all have that IP.

That tcpipguide link about Class D addresses has a table with more than the table on the wikipedia page on classful addressing.

I suppose in this case not defined means no network fields and host bit fields which is what you say you read, which makes sense and I think that's what the wikipedia page really meant when it said undefined. There are also going to be some addresses that IANA never assigned..but no doubt some multi-cast addresses were given out.

I don't know if you'd call the whole thing a network address. Network address is normally an address ending in .0 representing the subnet. I don't think a multi-cast address is referred to as a network address.