BSCI question, any ideas?

Hello fellow studyers. I've got the following test question that I'm not sure about, wonder if anyone could tell me what they think the answer is and give their reasons? It has me stumped.

Regards Paul

Which one of the statements below regarding classful and classless routing protocols is correct?

A. In a classful system, a router uses a bit mask to determine the network and host portions of an address and there is no class restriction. B. In a classless system, a router determines the class of an address and then identifies the network and host octets based on that class. C. In a classful system, subnet mask information is maintained and passed along with each routing update. D. In a classless system, when a routing update is received about a different major network as configured on the receiving interface, the default subnet mask is applied. E. In a classful system, when a routing update is received about the same major network as configured on the receiving interface, the router applies the subnet mask configured on the receiving interface.

many thanks for the reply Doan,

This may sound like a very elementary question but is "bit mask" just short for "subnet mask"?

Regards Paul

Im not Doan but I'll put this out there:

Basically a bit mask is a subnet mask written in binary. Instead of

255.255.255.0 you have 11111111.11111111.11111111.00000000

When your deal> many thanks for the reply Doan,

Thanks Nick.... I'm not too bad with the old binary but I must admit I tend to think more in decimal and just rememering that 252's go up in 4's, 248's go up in 8's etc. any tips on 'thinking in binary' greatly appreciated!

Regards Paul

I had a wonderfully written easy to understand explanation that would have burned subnet bitmasks indelibly into your head... Then Thunderbird crashed....

Real quick this time (kids need to hit the rack):

A teacher in a CCNA class showed me how to write the following chart. It may be well known but its the only place I have seen it.

Octet:

1 1 1 1 1 1 1 1 A 1 2 3 4 5 6 7 8 B 128 64 32 16 8 4 2 1 C 126 62 30 14 6 2 0 0 D 128 192 224 240 248 252 254 255 E 2 4 8 16 32 64 0 0 F

A. Subnet bits (dont know why I place this) B. Bit Placement C. Bit "worth" (cant think of the terminology) D. Number of hosts per subnet E. Subnet Mask F. Number of Subnets. This is using all 0's and all 1's. Minus 2 for each one if you are avoiding it. I don't recall what Cisco recommends.

You d> Thanks Nick.... I'm not too bad with the old binary but I must admit I tend

thanks Nick, I think I'll jot that down when I get into the exams in future, undoubtably useful. Cheers