MSPress question

Spacer_08Spacer_08 Member Posts: 39 ■■□□□□□□□□
Hello! Please could someone help me on this one. The question can be found on 13-8 of ms press 70-291 (1st edition).

Question:

Your organisation has leased the class c network 199.205.14.0/24. You are subnetting this network using VLSM. Your routers support the zero subnet and the longest match algorithm. You ask one of your support staff to design a subnetting structure but when she submits this you suspect that some of the network/subnet mask allocations are invalid. Which of the following are not valid networks?

A) 199.205.15.64/25
B) 199.205.15.192/26
C) 199.205.15.130/26
D) 199.205.15.96/26
E) 199.205.15.8/27
F) 199.205.15.40/28

I chose A, C, D, E and F. And MS press says only A, C, E are correct. After reviewing their explanation as to why D and F were not correct, it states:

D) Mask = 255.255.255.224
Increment = 256-224 = 32

F) Mask = 255.255.255.248
Increment = 256-248 = 8

This is what stumped me, why does it state the mask is .224 when /26 = 192? And with F why does it state .248 when /28 = 240.

Thanks in advance!

Comments

  • gojericho0gojericho0 Member Posts: 1,060
    You are correct. That does appear to be an error in the MS book
  • dynamikdynamik Banned Posts: 12,314 ■■■■■■■■□□
    http://support.microsoft.com/kb/830785/en-us

    That's listed in the errata.
    On page 13-8, the possible answers for objective 1.1 question 2 read:

    "A. 199.205.15.64/25
    B. 199.205.15.192/26
    C. 199.205.15.130/26
    D. 199.205.15.96/26
    E. 199.205.15.8/27
    F. 199.205.15.40/28"

    They should read:
    "A. 199.205.15.64/25
    B. 199.205.15.192/26
    C. 199.205.15.130/26
    D. 199.205.15.96/27
    E. 199.205.15.8/28
    F. 199.205.15.40/28"
  • snadamsnadam Member Posts: 2,234 ■■■■□□□□□□
    yep, and just for the record, it is corrected in v2. The questions dont start until 13-11. It threw me off until I realized OP was using v1 :D
    **** ARE FOR CHUMPS! Don't be a chump! Validate your material with certguard.com search engine

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  • dynamikdynamik Banned Posts: 12,314 ■■■■■■■■□□
    snadam wrote:
    It threw me off until I realized OP was using v1 :D

    You better work on your reading comprehension skills or those MS tests are going to eat you alive icon_lol.gif

    I just ran over it, and the changes in the errata make D correct, but F is still wrong. Looks like they forgot to change F to /29 icon_rolleyes.gif

    /25
    0
    128

    /26
    0
    64
    128
    192

    /27
    0
    32
    64
    96
    128
    160
    192
    224

    /28
    0
    16
    32
    48
    64
    80
    96
    112
    128
    144
    160
    176
    192
    208
    224
    240
  • snadamsnadam Member Posts: 2,234 ■■■■□□□□□□
    dynamik wrote:
    snadam wrote:
    It threw me off until I realized OP was using v1 :D

    You better work on your reading comprehension skills or those MS tests are going to eat you alive icon_lol.gif


    thats why I read the questions twice over! :)
    **** ARE FOR CHUMPS! Don't be a chump! Validate your material with certguard.com search engine

    :study: Current 2015 Goals: JNCIP-SEC JNCIS-ENT CCNA-Security
  • Spacer_08Spacer_08 Member Posts: 39 ■■□□□□□□□□
    Thanks very much guys. And thanks for the link dynamik, I think i'll spend more time reading that than the books themselves! And yes, it appears F is still wrong on the corrections list :o
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