What IP Class is it?

ch1vas

Hello,

I started studying for my CCENT,CCNA about 2weeks ago. I'm in the middle of IP Addressing. Question:

Is this IP address: 150.150.1.0 a Class C or a Class B IP?

I'll explain why I'm confused after I get some answers .

Ltat42a

Have you tried writing this IP out in binary? That will give you your answer too.

jdballinger

That's a class B address.

MAC_Addy

ch1vas wrote: »

I'll explain why I'm confused after I get some answers .

That's an odd part to add to your post...

xXErebuS

Ltat42a wrote: »

Have you tried writing this IP out in binary? That will give you your answer too.

No it wont... and it all depends if your talking about classful networks; if you are then jd is correct... see below

Classful network - Wikipedia, the free encyclopedia

Please note in real world one may say use the network 10.10.10.0 and if you ask what mask they may say use a class C on it; that simply means its 10.10.10.0/24. As to standard generalization rule for classful routing see wikipedia link.

ch1vas

I was confused because it says that if an IP starts with 128-191 it's a Class B IP but at the same time x.x.x.0 indicates a Class C IP.
So I'm a little confused when which rule applies? Or I'm just misunderstanding something...

networker050184

xXErebuS wrote: »

No it wont... and it all depends if your talking about classful networks; if you are then jd is correct... see below

Classful network - Wikipedia, the free encyclopedia

Please note in real world one may say use the network 10.10.10.0 and if you ask what mask they may say use a class C on it; that simply means its 10.10.10.0/24. As to standard generalization rule for classful routing see wikipedia link.

Yes it will. Just because something has a /24 mask does not mean its a class C address. The classes are well defined though mostly outdated due to VLSM.

Ltat42a

The first octet - 150, written in binary = 10010110. The first 2 bits (10) is in the Class B range.

suresh.palacharla

that is a class b

ch1vas

Ltat42a wrote: »

The first octet - 150, written in binary = 10010110. The first 2 bits (10) is in the Class B range.

Oh I see. Darn, I thought the Classes are defined by the actual IP address and not by the binary number.

Thanks for clarifying.

networker050184

The binary is the IP address, just not in dotted decimal form. Its the same thing either way just a different way of expressing it.

Ltat42a

^ True, true. Computers & networking devices talk binary, we humans like to talk decimal.

ch1vas

ch1vas wrote: »

Oh I see. Darn, I thought the Classes are defined by the actual IP address and not by the binary number.

Thanks for clarifying.

Hm, after thinking about it, I'm still confused because 150.150.1.0 indicates that only the last octet is for Hosts and according to the book I'm reading (Wendell) that would be a class C IP (x.x.x.0) but it also says that 150 should be a Class B as it falls between 128-191.
And now I got a third explanation that 10010110 is a Class B but 10 would actually fall between 1-126 which would be Class A?

I'm totally confused now

networker050184

You are mixing two things together.

First you have classful address ranges that are predefined (A, B, C etc). These are what you are looking for in the first octet.

Second you are looking at VLSM which allows you to use classless addressing where in you can assign any length mask to any class.

In the end the mask length has nothing to do with address class when thinking in the current classless world of addressing.

ch1vas

networker050184 wrote: »

You are mixing two things together.

First you have classful address ranges that are predefined (A, B, C etc). These are what you are looking for in the first octet.

Second you are looking at VLSM which allows you to use classless addressing where in you can assign any length mask to any class.

In the end the mask length has nothing to do with address class when thinking in the current classless world of addressing.

Ahh now you enlightened me . So their are two different ways to determine the class.. one without subnetting and one with subnetting.

networker050184

No, there is one way to determine address class. Look at the first octet.

showbo

If you are just determine what class of address it is, networker is right, just look at the first octect.
1
2
3
.....
126 is class A

128
129
130
......
191 is class B

192
193
194
.....
223 is class C

NetworkVeteran

ch1vas wrote: »

150.150.1.0 indicates that only the last octet is for Hosts

The first octet in 150.150.1.0 indicates the class, as networker says.

Further, 150.150.1.0 does not indicate "only the last octet is for hosts." This address could belong to the 150.0.0.0/8, 150.150.0.0/16, or 150.150.1.0/24 network.. among other possibilities. If you could determine the subnet mask from the IP address, there'd be no need to configure masks when using the "ip address" command, or in DHCP messages, or in routing protocol messages. Additional food for thought.

Michael2

Just remember the values for the first octet in each class.

1-126=class A
128-191=class B
192-223=class C

There's also a class D and class E but those are experimental. I encountered a question on my exam sim which includes one of those, but it was only one question.

NetworkVeteran

Michael2 wrote: »

There's also a class D and class E but those are experimental.

Class D is assigned for IP Multicast.

Class E is experimental. On second thought, class E is for all intents and purposes dead.