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.
![enter image description here](../../I/static/images/61a4e553b63ea1c8ac7e3f63141fe51613783e68d5dfc724e135a053f17b140f.png)
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.
It looks like you read right. "I read somewhere that D ip addressas are 32-bit network addresses and they dont have hostID," ok you're wrong that it's a 32-bit network address. Network address is something else, network address is an IP ending in .0 But on the other aspect it seems you're right that Class D doesn't have a network and host portion. Maybe was a good source you read. Where did you read that? – barlop – 2011-05-27T09:14:24.550
you are righ, I made a mistake. I got the site material wrong. http://www.paessler.com/support/kb/questions/34
– Roshio – 2011-05-27T10:10:21.390