welcome to back! tcp/ip subnetting pop quiz tcp/ip cheat sheet
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Welcome to Back!
TCP/IP Subnetting
Pop Quiz
TCP/IP Cheat Sheet
IP Addresses
IP Address: 192.168.5.201
Network Portion: 192.168.5.201
Node Portion: 192.168.5.201
• Every IP Address has a node portion and a network portion
Subnet Mask
IP Address: 192.168.5.201
Subnet Mask: 255.255.255.0
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Network ID: 192.168.5.0
•The subnet mask tells us which part of an IP address is the node portion vs. the network portion•An IP address without a subnet mask is meaningless
Binary ANDing
• AND is a mathematical operator just like
+ (plus) and – (minus)
• 1 + 1 = 2
• 1 AND 1 = 1
AND Truth Table
A | B | A AND B---------------------------------------FALSE | FALSE | FALSEFALSE | TRUE | FALSE TRUE | FALSE | FALSETRUE | TRUE | TRUE
AND Truth Table
A B A AND B-----------------------------0 0 00 1 0 1 0 01 1 1
AND Truth Table
0 AND 0 = 00 AND 1 = 01 AND 0 = 01 AND 1 = 1
1100000010101000000001011100100111000000.10101000.00000101.11001001
Man vs Machine• Human readable dotted decimal notation
192.168.5.201
– Each number represents an “Octet” or 8 bits
• What the computer sees:
Subnet Mask and ANDing
• IP: 192.168.5.201
• Subnet: 255.255.255.0
IP: 11000000.10101000.00000101.11001001
Subnet: 11111111.11111111.11111111.00000000
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11000000.10101000.00000101.00000000AND
IP: 11000000.10101000.00000101.11001001
Subnet: 11111111.11111111.11111111.00000000
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11000000.10101000.00000101.00000000
TCP/IP Cheat Sheet: The Rules
• The Subnet/network address is always hidden behind the 1s in the mask
IP: 11000000.10101000.00000101.11001001
Subnet: 11111111.11111111.11111111.00000000
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11000000.10101000.00000101.00000000
TCP/IP Cheat Sheet: The Rules
• The Host/Node address is always hidden behind the 0s in the mask
IP: 11000000.10101000.00000101.11001001
Subnet: 11111111.11111111.11111111.00000000
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11000000.10101000.00000101.00000000
192.168.1.250= .11111010 --------------
10000000
192.168.1.5= .00000101 --------------
00000000
TCP/IP Cheat Sheet: The Rules
(Except in special cases)
• The all-1s and all-0s subnet addresses are invalid (but NOT in CIDR)
Ex.
Network ID 192.168.1.0 Subnet Mask 255.255.255.128 ->11111111.11111111.11111111.10000000
0s hide the host
address
1s hide the subnet addressBreaks the rule! (except in CIDR)
These bits belong to the Big IP in the Sky
(we can’t change them)
These are the bits that we
own
TCP/IP Cheat Sheet: The Rules
(Except in special cases)
• The all-1s and all-0s host addresses are invalid (Always)
Ex.
IP Address: 192.168.1.0Subnet Mask: 255.255.255.0
ORIP Address: 192.168.1.255Subnet Mask: 255.255.255.0
Reason Behind the Rule
• The all zeros host address is the same as the network ID
Ex. IP: 192.168.1.0Subnet: 255.255.255.0
----------------------------------------Network ID:192.168.1.0
• The all ones host address is reserved for the broadcast address
Practice Problems
• 1 AND 1
• 1 AND 0
• 0 AND 1
• 0 AND 0
• 1111 AND 1010
• 0000 AND 1010
• 110101 AND 1101110
Practice Problems
• 110010b to Decimal
• 137d to Binary