Subnetting example

[hiyalim]

I pulled this example from the net but I think it is wrong.

IP Address: 192.168.0.4
Subnet Mask: /29 (255.255.255.248)

/29 reflects that there is a network that consists of eight IP addresses; 192.168.0.0 to 192.168.0.7. The 192.168.0.4/29 is then 5th IP address of the network.

I think the answer should be:

eight IP addresses: 192.168.0.4 to 192.168.0.11. The 192.168.04/29 is the 1st IP address of the network. Correct?

[Rob Burchard]

Hi @hiyalim ,

The answer you found on the net is correct. The 192.168.0.4/29 address breaks down like this.

Address range is 192.168.0.0 - 192.168.0.7

Subnet  addr = 192.168.0.0

Broadcast addr = 192.168.0.7

Host range = 192.168.0.1 - 192.168.0.6

/29 cidr mask converted to dotted decimal = 255.255.255.248, chunk size = 8

After learning subletting the manual way as taught in CCNA curriculum, I found it beneficial to memorize and understand the subnet sizes as represented in CIDR, how those CIDR notations mapped to dotted decimal and how each of those represented a range of addresses, sometimes referred to as chunks.

Here is an example Working up from a /24:

CIDR:DECIMAL:CHUNKS (ranges)

/24 : 0     : 256

/25 : 128 : 128

/26 : 192 : 64

/27 : 224 : 32

/28 : 240 : 16

/29 : 248 : 8

/30: 252 : 4

/31: 254 : 2

/32: 255 : 1

Hope this helps! If it did please rate!

Thanks,

Rob

[luis_cordova]

Hi @hiyalim 

No, the network mask indicates until which bit of the IP address corresponds to the network address.
For example, in a mask /29:

1100 0000.1010 1000.0000 0000.0000 0 | 100 = 192.168.0.4/29

1111 1111.1111 1111.1111 1111.1111 1 | 000 = 255.255.255.248 = /29

All the bits to the left of the mask are network address bits and the bits that are to the right of the mask are host bits.

In all network addresses the host bits are all in zeros:

1100 0000.1010 1000.0000 0000.0000 0 | 000 = 192.168.0.0/29

Then, the valid host IP addresses of this network are:

1100 0000.1010 1000.0000 0000.0000 0 | 001 = 192.168.0.1/29

1100 0000.1010 1000.0000 0000.0000 0 | 010 = 192.168.0.2/29

1100 0000.1010 1000.0000 0000.0000 0 | 011 = 192.168.0.3/29

1100 0000.1010 1000.0000 0000.0000 0 | 100 = 192.168.0.4/29

1100 0000.1010 1000.0000 0000.0000 0 | 101 = 192.168.0.5/29

1100 0000.1010 1000.0000 0000.0000 0 | 110 = 192.168.0.6/29

1100 0000.1010 1000.0000 0000.0000 0 | 111 = 192.168.0.7/29

Regards