Good subnetting white paper PDF

I found this good pdf document on subnetting. It is pretty good.

Subnetting PDF (Click Here)


6 Responses to “Good subnetting white paper PDF”

  1. how do you reverse engineer a summurized route to find out which routes wil be routed given a particular summarized route

    • Samuel
      First I do not like the way these questions are formatted it is definitely deceiving but with practice manyou will get it.I did a crappy job explaining but the bottom line is this. YOu have to find the subnet ranges. First they give you the network id (first non-usable ip address in a subnet range) then the give you the subnet mask in / (slash notation) first one is /20 or /21.
      Then you conver to bit notation. You do not have
      conver entire network id into bit notation just the first non common octet as I show below. Then find the interval/increment with the bit notation as I did.
      Then you can make your ranges from that. For sure they are going to make sure you know what the first ip and the last ip in the subnet range is. The first and last are non-usable. They give you ip addresses just make sure they are within the range and you have it. Yeah at first glance it does look like a route summary problem but it is a simple subnetting question of find the range and see which fit into the range. Go to and practice subnetting 30 minutes daily and never stop. Good luck man.
      Robert 😉

      The five Ethernet networks connected to router Certkiller 1 in the
      graphic have been
      summarized for router Certkiller 2 as Based on this information,
      which of the following packet destination addresses will Certkiller 2 forward to
      Certkiller 1, according to this summary? (Choose two.)
      Samual watch this like G said it is subnetting. You need to find the range of subnet addresses
      then rule out the first non-usuable host (network ID) and then out rule the last non-usuable host(broadcast) /20 has – (network id and broadcast)
      A. is not in range so NO
      B. yes, is in range so yes!
      C. is not in range so No
      D. yes, it range so yes
      E is not in range so no
      F is not in range so no
      G not in range at all so no

      Answer is B and D –

      The question below is same; these are subnetting find the range questions. not route summary calc.
      It looks like it but really it is just subnetting to find the range and make sure numbers fall into it.
      128 64 32 *16 8 4 2 1
      192.1.1 0 0 1 0 0 0 0.0000000
      /20 the 20th place to the right. the last bit 16 is the increment.
      /if it was /21 the 8 would be the interval or increment for each subnet range.


      In this network segment, the IP subnets connected to router Certkiller
      2 have been
      summarized as a route and sent to Certkiller 1. Based on this
      information, which two packet destination addresses will Certkiller 1 forward to
      Certkiller 2? (Choose two)
      Find the range:
      1. /21 they give you the first address or network id
      2. find the increment. 192.18.176 to ,
      192.18.+8.0=184 increment is 8..use first range above to ,

  2. Hey guys,
    Just thought I should share with you a resource that’s come in very handy in my travels….there are many good articles on subnetting and the like at, including one on subet planning. Best of luck!
    –Robert Marshall

  3. Hi
    is it possible to reverse engineer a given summery route to find the network addresses or rather ip addresses?
    given a summery route ;

    • think about your question. say for example I had an summary of this 192.168.1.x /25

      look how many ip addresses you can make from /25 and you can make a ton of addresses from /22.

      now if you had this 192.168.1.x /30…you could narrow it down to 2 addresses.

      get it…in your case it is going to be hard but you can say ping that range maybe
      but to find it going to be hard….it will take you a lot of tries..because it is summarizing many things
      I would say going to be hard I not dare say impossible because a lot is possible but going to be hard…

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