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Home > Archive > CCDA/CCDP > March 2004 > Subnetting question
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Subnetting question
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| This is from a Cisco practice exam, in their e-learning section.
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If Mask 255.255.248.0 were used with a Class B network, how many subnets will exist, with how many hosts per subnet, respectively?
Incorrect: 14 and 4096
Correct: 30 and 2046
Incorrect 510 and 126
Correct: 1022 and 62
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Yes two correct answers. I was befuddled when taking it, as it indicated you were to choose two. I don't get it. I understand the 30/2046. But I don't understand the 1022/62?
That would be a mask of 255.255.255.192 wouldn't it?
Confused puppy. | |
| OHCCNP2003 2004-03-07, 11:22 am |
| Looks like Cisco made a mistake in their exam material. For 62 and 1022 the mask would be 255.255.252.0. | |
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| Just to be sure, I think I am right on 192. For 1022 subnets and 62 hosts, you need 10 bits for the subnet mask and 6 for the hosts. So you use 8 bits from the third byte, = 255, leaving you to "borrow" two more from the last byte, 1100 0000 = 192.
Right? | |
| ewright 2004-03-08, 9:51 am |
| According to the trusty IP Subnet calculator you're right. | |
| Demijohn 2004-03-08, 3:05 pm |
| Another example of why not to rely too much on those crappy test Q&As, even if they're from Cisco. | |
| s2kfan 2004-03-08, 9:39 pm |
| I've encountered many mistakes on exams. If I find discreapancies from coursebook, website and Cisco Press books, I will go with course notes as they are usually based on the courses. |
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