What is the deffirent between Classfull network and Classless network ?

Classful networks use the 'classful' subnet mask according to the leading bits in the first block of the IP address:

Class A begins with binary0 (0-127.x.x.x)

So and IP address0.0.0.0 to127.255.255.255 use subnet mask =255.0.0.0

Class B begins with binary10 (128-191)

So IPaddresses128.0.0.0 to192.255.255.255 use subnet mask =255.255.0.0

Class C begin with binary110 (192-223)

So IP addresses192.0.0.0 to255.255.255.0 use a subnet mask =255.255.255.0

Classless IP addressing means you can use any subnetmask you want, even assigning partial blocks. For example subnet172.16.0.0 is a class B network.

But you have two physical interfaces on your router that connect to switches with5 VLANs. Classless routing allows me to break up this IP address into more useful segments.

Switch1                                   Switch2

VLAN1    172.16.1.0/24               VLAN10    172.16.10.0/24

VLAN2    172.16.2.0/24               VLAN11    172.16.11.0/24

VLAN3    172.16.3.0/24               VLAN12    172.16.12.0/24

VLAN4    172.16.4.0/24               VLAN13    172.16.13.0/24

VLAN5    172.16.5.0/24               VLAN14    172.16.14.0/24

So I have made10 useful subnets from a single network. Here's the real advantage:

1. When my router is configured for classless routing it can advertise all10 networks as one IP address 172.16.0.0255.255.240.0, or I can advertise each physical interface using 172.16.0.0 and 172.16.8.0 using ths subnet mask 255.255.248.0

2. I still have spare room in the172.16.0.0/16 for lots more subnets. If I want to create another group, do the binary math, I find the next available subnets are172.16.24.0255.255.248.0. If I use the #no auto-summary command on my routing protocol. I can place the new172.16.x.x subnets anywhere in my network.

#auto-summary tells my router I only want to use classful subnetmasks.

Buy The CCNA study guide. The appendixes on how to calculate subnet masks with VLSM really helped me.

Sorry of the explanation is a bit long. Best of luck

Abdus

So an IP address consists of network and host portion.  For example, /24 notation means that first24 bits are dedicated to the network portion and they remain the same for all hosts in the network, whereas, the last8 bits uniquely identify each host in the network.  Now to answer your question in short, classful addressing divides IP addresses into5 different classes, each with its own predefined address range and subnet mask.  On the contrary, classless addressing can set the network boundary practically anywhere, thus breaking the classful limitations.

Classless addressing is the preferred method for assigning IP addresses, mainly because it saves address space

For somebody with not so much technical exposure the answer is : A Clasfull ip Adress means that , the address falling under that category follows and respect the universal rule of network addressing.

And those ip address falling under the classless ip schemes, Does not respect and follow the universal guidlines .

However both the categories are in use in our current technological era .

Classfull Ip address: Classful Ip address is take only the pre-defined bits in Network ID (8,16,24) in addressing. Example. Class A pre-defined bits -810.2.1.10 /8, Class B Pre-defined bits -16172.16.1.20 /16, Class C Pre-defined Bits -24192.168.1.30 /24 This type of address is called Classful Ip address.

Class A=255.0.0.0 , Classs B:255.255.0.0 Class C=255.255.255.0 Classless Ip Classless Ip address is assign any number of bits in network ID is called Classless IP address. Example10.2.1.10 /12. Bits barrow from Host Id added in to Network id. This called Classless Ip address.

Example: Class A: IP10.0.0.0 /9 => sub net =255.128.0.0 Class B: Ip172.0.0.0 /18 => Sub net =>255.255.192.0 Class C: IP192.0.0.0/27 =>sub net =>255.255.255.224

The classfull address which maintains the default subnet mask. i.e-192.168.1.1/24 its classfull adress in which u will get254 host usable ip. but if we need to create CIDR like, if u have differrent dipartment and u want to only12 IPs then you will configured /29 pool. In this case your network will be classless.

classfull means that it dosn't support subnetting so you will use the default class like A,B,C .. 

classless it understand and support subnetting

It is recommended that you use classless IP addressing. Where you can subdivide a classful network into subnets and avoid wastge of remaining IP addresses. For example, suppose you have got50 devices in your network which needs to be configured with an IP address. Here you can go with class C network192.168.0.0/24, which will give you255 IPs(actually253 that can be configured on hosts). But in real time, you don't want that much IP addresses, you only need50 IPs. So if you go with the above C class /24 subnet, you are wasting the remaining200+ IPs. Instead if you go with subnetting (Classless IP addressing) you can further subdivide it to /25 or /26 network where you will be able to use a smaller subnet from the192.168.0.0 Network and at the same time you can make use of the rest IP addresses. Please let me know if you need any clarifications.

Hi,

Classful means if you will use class A or B or C in your network then you must use the default mask of the selcted class.

The default masks:

• Class A:255.0.0.0
• Class B:255.255.0.0
• Class C:255.255.255.0

Classless means you can use subnetting or supernetting with your calss, in other words you can use any prefix for any class, but before doing this you have to plan, desing and do some calculations before assing subnets and their masks.

HTH

Best Regards,

Classful is based on the default Class A,B or C networks.

- Class A:0 -127 with a mask of255.0.0.0 (/8)

- Class B:128 -191 with a mask of255.255.0.0 (/16)

- Class C:192 -223 with a mask of255.255.255.0 (/24)

All devices in the same routing domain must use the same subnet mask. Since routers running a classful routing protocol do not include subnet mask information with routing updates, the router assumes either its own subnet mask, or defaults to the classful subnet mask.

Classless on the other hand, allows the use of variable length subnet masks, or VLSM, because subnet mask information is included with routing updates. You can have a mixture of different subnet masks in the same routing domain:

-10.1.0.0/19

-10.2.0.0/20

-172.16.8.0/21

-172.16.16.0/24

In simple words: using the Default Class subnet (Five Class A,B,C,D.,E) are Classfull addresses while using Variable subnet mask (making Own subnet ) are classless Addressses.

Your default class addresses are Class A0-127, Class B -128-191 Class C -192-223 for the1st octet values Classful ip addresses are ip addresses that follow this standard subnet ranges for class A, B, C so a classful router protocol like ripv1 will always assume that the address172.16.1.2 has a subnet mask of255.255.0.0 even if you want it to have a subnet of255.255.255.0 so on a classful router protocol172.16.1.2 will always have the range172.16.0.0 -172.16.255.255 (because the value172 in the1st octet falls in the Class B range of128-191 and class B addresses have the subnet mask set to255.255.0.0)Classless ip addresses mean that the address range is determined by the subnet mask and hence the same address172.16.1.2255.255.255.0 will now be looked at as having its range as172.16.1.0 -255 because255.255.255.0 corresponds to that range. P.S. Rip was updated to support this (ripv2)