| Author |
Broadcast Confusion?
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| justindu 2003-09-28, 12:10 am |
| What is the subnet broadcast address that the host 172.16.10.12 with 9 bits of subnetting use?
A 172.16.10.127
B 172.16.255.255
C 172.16.255.0
D 172.16.255.128
Why is the answer A?
Wouldnt the first network be 128 with a broadcast address of .191? | |
| martek 2003-09-28, 12:19 am |
| 172.16.10.12 belongs to the 172.16.10.0 subnet. Since the subnet mask is 255.255.255.128 (9 bits used for subnets), the subnet IDs increment by 128, so the broadcast address for this subnet is 172.16.10.127.
And the first subnet for 172.16.10.12/25 is 172.16.0.0 (subnet zero).  | |
| justindu 2003-09-28, 12:40 am |
| ahhh that dam subnet zero.. LOL
I thought that was invalid on ccna??
This was a question in Todd Lammles book. | |
| Humbug 2003-09-28, 3:57 am |
| Subnet zero is not valid, unless you see it explicitly (ip subnet-zero)
172.16.10.12
Original Mask:255.255.0.0
Subent Mask: 255.255.255.128
Current subnet: 172.16.10.0
Next subnet:172.16.10.128
The rule is: Broadcast address is the next subnet address minus 1.Hence,
172.16.10.127
Learn from Wendell Odem book, he is teaching subnetting better than anybody else. | |
| NetStroller 2003-09-29, 12:01 am |
| Be sure to remember the CCNA exam does not cover subnet-zero. Worry about it for the more advanced tests. |
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