Now to answer your question in short, classful addressing divides IP addresses into 5 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 …

Classful means: class A,B, and C then the mask /8, /16 and /24 respectively. there is no subnet. Then on classless you can barrow bits from host to become a subnet. Expand Post

This is an additional explanation to the table on Classful addressing in exam certification guide, Pg 110, ICND1, by Wendell Odom

I am trying to understand the difference between classful and classless IP addressing. I understand the rules for classful addressing, but I am less sure about classless addressing. If I want to use classless IP networks, can I ignore the class of the IP address completely? Can I have a IP address something like 172.17.2.15/6? Thanks, Logger

Hi All, Im a bit confused as to the difference between classless and classful addressing, I understand that classful has 3 parts network, subnet and host, which means a class A B or C network that can be subnetted such as 192.168.5.0/26 (a class C …

then it will be classful like rip v1. However if you include the no auto-summary then it is classless. this is very easy to test with a packet tracer examples. here is a listing from my pkt tracer where you can see that Router rip has recognised that the172.16.0.0 network is actually. two networks: 172.16.1.0 & a 172.16.2.0

Classful routing protocols having simpler routing updates because the subnet mask is not sent in the update. It can instead be determined using the first octet to determine the class of the address and from there it knows the default subnet mask. That part makes sense but what is confusing me is when you filter in subnetting.

IP Range starts 1-126 & default mask -> Call it class A, or a classful address. IP Range starts 128-191 & default mask -> Call it class B, or a classful address. IP Range starts 192 - 223 & default mask -> Call it class C, or a classful address . If not using defaults masks, don't worry about the classes which the address belongs to.

You have no "classful" network to be redistributed. The 172.16.100.0/24 is not "classful", therefore no route is redistributed. Even if you add the static route. With the static route you will need to use "redistribute static" command rather than "redistribute connected". So your options: (1) redistribute connected subnets

Classful vs classless routing--ip classless (default) vs no ip classless . This has to do with how the default route is used. With "ip classless", packets destined to an address are strictly matched against the most specific route in the route table. If no match exists, the default route can be used. Classful (no ip classless) changes this a bit.