question on subnetting....

sambuca69sambuca69 Member Posts: 262
in CCNA & CCENT
I've been practicing some subnetting on subnettingquestions.com - Free Subnetting Questions and Answers Randomly Generated Online and I'm a bit confused on an answer they had to a question.

Question was: What valid host range is the IP address 192.168.155.4 255.255.255.248 a part of?

Their answer: 192.168.155.1 through to 192.168.155.6

Now, I came up with 192.168.155.1 - 192.168.155.7. The IP ranges should be every 8 IP addresses, so you have an initial range of 192.168.155.0 - 192.168.155.8. You can't use the first or last IP.

What am I missing here?
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Comments

  • hodgey87hodgey87 Member Posts: 232
    Yeh there answer is correct if you look out how it all forms out

    0 8 16 24 etc
    1 9 17 25 1st usable
    6 14 22 30 last usable
    7 15 23 31 broadcast

    you cant use the actual subnet number ie 0, 8, 16 and you cant use the broadcast for each subnet ie 7, 15 etc.
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  • blackninjablackninja Member Posts: 385
    The subnets go up in mutiples of 8:

    192.168.155.0
    192.168.155.8
    192.168.155.16
    etc.

    therefore:
    192.168.155.0 (subnetwork address, not assignable)
    192.168.155.1 (valid address, assignable)
    .
    .
    192.168.155.6 (valid address, assignable)
    192.168.155.7 (broadcast address, not assignable)

    192.168.155.8 (next subnet address)

    Hope thias helps
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  • sambuca69sambuca69 Member Posts: 262
    Ahhh..... broadcast address. I overlooked that. Many thanks for clearing it up :)
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  • mikej412mikej412 Member Posts: 10,086 ■■■■■■■■■■
    sambuca69 wrote: »
    The IP ranges should be every 8 IP addresses, so you have an initial range of 192.168.155.0 - 192.168.155.8.
    You have 9 addresses there. The first range is 192.168.155.0-192.168.155.7

    Take out the network address and broadcast address and you have the host addresses that match the answer given by subnettingquestions.com
    :mike: Cisco Certifications -- Collect the Entire Set!
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  • KaminskyKaminsky Member Posts: 1,235
    sambuca69 wrote: »
    Ahhh..... broadcast address. I overlooked that. Many thanks for clearing it up :)

    Nope ... You thought initial range was 0 .. 8
    sambuca69 wrote: »
    ... so you have an initial range of 192.168.155.0 - 192.168.155.8.

    It isnt, 8 is the start of the next subnet.

    Thing about subnetting is you get loads of shin bruises where you keep having to kick yourself icon_sad.gif
    Kam.
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  • blackninjablackninja Member Posts: 385
    sambuca69 wrote: »
    Ahhh..... broadcast address. I overlooked that. Many thanks for clearing it up :)

    Don't worry, I really struggled with subnetting at first, then literally one night while thinking about it - it all just clicked.

    When it does click, you will think that you where stressing for no reason.

    Just keep at it.
    Currently studying:
    CCIE R&S - using INE workbooks & videos

    Currently reading:
    Everything. Twice ;)
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