From: Jai Prakash (jpjsr06@gmail.com)
Date: Thu May 18 2006 - 14:25:12 ART
Hi Frog
As per my understanding, when u take calss C as a major network and
divides into subnets, it takes all available subnets with valid hosts.
In your case, if you divide 192.168.1.0/24 into subnets of 30 block host
IP.........you will get 8 valid subnet blocks with each having 30 valid
hosts IP. You can use any subnet from these 8 subnets block.
The theory says.....don't use 1st IP and the Last IP of the subnets because,
they represent Network IP and Broadcast IP accordangliy for that particular
subnet.I never seen that books says don't use 1st subnet and last subnet,
when you divide Major Network into subnets.
The whole discussion outcome is :
Ans of 1st Qusetion ) U can use 1st and Last subnet of Major Network
Ans of 2nd Qusetion ) Subnet mask for /25 will be 255.255.255.128 ( Here U
can use 2
valid Network subnets with 126 valid host
IPs in each subnet)
Subnet mask for /26 will be
255.255.255.192( Here U can use 4
valid Network subnets with 62 valid
host IPs in each subnet)
Subnet mask for /27 will be
255.255.255.224 (Here
U can use 8
valid Network subnets with 30 valid host
IPs in each subnet)
Correct me , if I m wrong................
Best Regards,
Jai
On 5/18/06, Radioactive Frog <pbhatkoti@gmail.com> wrote:
>
> Hi Guys,
>
> Very basic question but lots of doubt.
>
> 1) First question:
>
> If class C subnet 192.168.1.0 is routed to ISP-B (small) by ISP-A (BIG
> ISP).
> When ISP B starts subneting the 192.168.1.0 IP block for different
> customer
> why do he starts distributing from the first subnet from 192.168.1.0/24
> (which sholdn't be used)???????????
> The books and theory says first and last subnet shouldn't be used (as
> network and broadcast subnets), hence we shouldn't use the
> 192.168.1.0/24(first subnet)
>
> Means the ISP should start distributing from second subnets e.g.
> 192.168.1.32 (see below).
>
> ---------------------------------------------------------
> Subnet , Valid Hosts , Broadcast
> 192.168.1.0 , 192.168.1.1 to 192.168.1.30 , 192.168.1.31
> 192.168.1.32 , 192.168.1.33 to 192.168.1.62 , 192.168.1.63
> 192.168.1.64 , 192.168.1.65 to 192.168.1.94 , 192.168.1.95
> 192.168.1.96 , 192.168.1.97 to 192.168.1.126 , 192.168.1.127
> 192.168.1.128 , 192.168.1.129 to 192.168.1.158 , 192.168.1.159
> 192.168.1.160 , 192.168.1.161 to 192.168.1.190 , 192.168.1.191
> 192.168.1.192 , 192.168.1.193 to 192.168.1.222 , 192.168.1.223
> 192.168.1.224 , 192.168.1.225 to 192.168.1.254 , 192.168.1.255
>
>
>
> 1) Second question:
>
> What if ISP starts distributing /25 /26 /27 IP blocks from 192.168.1.0/24IP
> block to the customers ? In this case what subnet mask shouldn't be used
> (still first and the last in 192.168.1.0/24 blocks) ?
>
> Appreciate your answers to this basic topic!
>
> Frog!
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:21 ART