pc/hosts ip address settings when making new network ids when subnetting RRS feed

  • 질문

  • Hello,

    I am studying for the Network + exam, and i am trying to better understand subnetting, making new network ids, and then putting pc's/hosts on those new network ids, and I was hoping i could ask this question about that.

    I (pretty much) understand how to extend a /24 subnet mask by 2 bits, and how that "makes" a /26 subnet mask, and also makes 4 new network ids.

    eg, if my original /24 network id was, and i extended the subnet mask by 2 bits to make it a /26 subnet mask...these would be the 4 new network ids, host ranges, and broadcast addresses

    network id, range..............................broadcast address - - - -

    if i had actually had 4 separate, physical networks with these 4 different network ids, and i had multiple pc's/hosts on each of them, then i could give the pc's/hosts ip addresses in the host range for that network id, but what would i give the pc's/hosts for their subnet mask address and their default gateway address?

    for the default gateway, I think if i had one router connecting the 4 new network id's, that router would need 4 interfaces, and each of those interfaces would need an IP address in the host range of the network id it was connected to, and then that router's interface's IP address would be the default gateway address for each pc/host in that network id. ...i think this is right..

    But if that is right, i am still confused about the subnet mask address for each pc/host.

    eg, if i convert a /26 subnet mask to dotted decimal, it would be, and that matches the 4th new network id.

    In fact, if i looked at the new subnet masks in binary as i figured out the new ip address host ranges, it seems the subnet mask was always the same as the network id.

    So, would be the subnet mask for all the pc's/hosts in all the new network ids?
    Is it possible for the subnet mask and the network id to be the same thing?
    Or am i missing something else entirely?

    Any help, or direction to any other help, would be greatly appreciated!

    2019년 9월 15일 일요일 오전 1:33

모든 응답

  • Hi,

    subnet masks are always contiguous 1s followed by contiguous 0s, so /26 mask is binary 1111 1111 1111 1111 1111 1111 1100 0000  or decimal

    What you have probably looked at is the subnet address BINARY multiplied by the subnet mask, and that will indeed render the subnet address for any IP out of that subnet. 

    four subnets are four different networks, don't let yourself be fooled by those A B C classes. So yes, a router for those four subnets needs a leg in each.

    Evgenij Smirnov

    2019년 9월 15일 일요일 오전 10:47
  • thank you for replying, and please pardon any delays in my responding as they are unavoidable for me at this time.

    there are several things i may be unclear on, so if i may focus in on one of the more specific questions i have: what would the ip configuration be for the clients in the 4 new networks?

    eg, in the 1st new network, if the router's connection to this network had an IP address of, would a client pc on this network have these IP settings?
    ip: (or anything else in host range)

    and if that is right, then how can the sm be the same IP address as the 4th new network's network ID?
    again, if I made the first calculation right, the 4th new network's network ID is also

    once again, thank you again in advance!

    2019년 9월 19일 목요일 오전 2:49
  • Hi,

    the SM is *NOT* 192.something. Read the first sentence of my reply, it's all there.

    Evgenij Smirnov

    2019년 9월 19일 목요일 오전 7:17
  • Hi ,

    Just want to confirm the current situations.

    Please feel free to let us know if you need further assistance.                   

    Best Regards,


    Please remember to mark the replies as an answers if they help.
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    2019년 9월 23일 월요일 오전 1:44
  • thank you for replying, Candy and Evgenij, 

    I understand my questions may be very fundamental, and they may possibly be misunderstood, or i may misunderstand part of a reply.

    With that said, in the scenario i described above with 4 "new" networks each with their own network id, i'm still confused about how one would enter a client's ip configuration in decimal.

    e.g. if there were a dhcp server available to these networks, what would the decimal values be for the clients' ip addresses, subnet masks, and default gateways? i missing something about "classless subnetting", eg are there no longer any such things as decimal subnet mask addresses? e.g. would i actually enter "/26" for the subnet mask instead of ""?

    thank you again, 


    2019년 9월 24일 화요일 오전 1:14