Lab 5.1: Subnetting Worksheet - savannahc502/SavC-TechJournal-NET215 GitHub Wiki

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LAB 5-1: Subnetting Worksheet

Challenge 1: Binary Decode of IP

  • Fill in the following table with the binary representations of the given IP/subnet mask combinations. Make Network ID bits RED, Make Host ID Bits BLUE

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Challenge 2: CIDR Notation to Dotted Decimal

  • Given the following subnet masks in CIDR (or β€œslash”) notation, what is the mask in dotted decimal notation?
    • A. /20 > Dotted Decimal = 255.255.240.0 | 11111111.11111111.11110000.000000
    • B. /26 > Dotted Decimal = 255.255.255.192 | 11111111.11111111.11111111.11000000
    • C. /22 > Dotted Decimal = 255.255.252.0 | 11111111.11111111.11111100.00000000
    • D. /30 > Dotted Decimal = 255.255.255.252 | 11111111.11111111.11111111.1111100
  • Given the following subnet masks in dotted decimal notation, what is the mask in CIDR (or β€œslash”) notation?
    • E. 255.255.224.0 > CIDR Notation = /19 | 11111111.11111111.11100000.00000000
    • F. 255.255.255.192 > CIDR Notation = /26 | 11111111.11111111.11111111.11000000
    • G. 255.255.255.252 > CIDR Notation = /30 | 11111111.11111111.11111111.11111100
    • H. 255.255.248.0 > CIDR Notation = /21 | 11111111.11111111.11111000.00000000

Challenge 3: Proper Subnet Mask

  • What would be the most efficient subnet mask for the following situations?

GitHub: To determine usable hosts of a network using the subnet mask, take 2 to the power of the number of host bits (the 0s) when the subnet mask is converted to binary. So, for /24 aka 255.255.255.0, the last 8 bits are the host bits. So, 2^8 is 256. The first and last IP address in a subnet net will be the network address id and the broadcast address, respectively.

  • Situation #1: A wireless network with 1,500 hosts β†’ /21 β†’ 11 bits for the host, 2^11 is 2,048 hosts
  • Situation #2: A backbone network with 9 hosts β†’ /28 β†’ 4 bits for the host, 2^4 is 16 β†’ next would be 3 bits, 2^3 is 8 (not enough)
  • Situation #3: A research lab with 54 hosts β†’ /26 β†’ 6 bits for the host, 2^6 is 64
  • Situation #4: A sales department network with 400 hosts β†’ /23 β†’ 9 bits for the host, 2^9 is 512