# TCP/IP Subnetting - Will Harper

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26 Οκτ 2013 (πριν από 4 χρόνια και 7 μήνες)

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TCP/IP Subnetting

Pop Quiz

TCP/IP Cheat
Sheet

My localhost
-
> 192.168.5.201

www.yahoo.com

-
> 87.248.113.14

Network Portion:
192.168.5
.201

Node Portion: 192.168.5.
201

Every IP Address has a node portion and a
network portion

255.255.255.0

----------------------------------------------------

Network ID: 192.168.5.0

is the node portion vs. the network portion

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

|

FALSE

FALSE

|

TRUE

|

FALSE

TRUE

|

FALSE

|

FALSE

TRUE

|

TRUE

|

TRUE

AND Truth Table

A B A AND B

-----------------------------

0

0

0

0

1

0

1

0

0

1

1

1

AND Truth Table

0 AND 0 = 0

0 AND 1 = 0

1 AND 0 = 0

1 AND 1 = 1

11000000101010000000010111001001

11000000.10101000.00000101.11001001

Man vs Machine

192.168.5.201

Each number represents an “Octet” or 8 bits

What the computer sees:

IP:

192.168.5.201

Subnet:

255.255.255.0

IP:

11000000.10101000.00000101.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------

11000000.10101000.00000101.00000000

AND

IP:

11000000.10101000.00000101
.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------

11000000.10101000.00000101
.00000000

TCP/IP Cheat Sheet: The Rules

hidden behind the 1s in the mask

IP:

11000000.10101000.00000101
.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------

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

-----------------------------------------------

11000000.10101000.00000101
.00000000

192.168.1.250= .11111010

--------------

1
0000000

192.168.1.5= .00000101

--------------

0
0000000

TCP/IP Cheat Sheet: The Rules

(Except in special cases)

The all
-
1s and all
-
0s
subnet
are invalid (but NOT in CIDR)

Ex.

Network ID

192.168.1.0

-
>

11111111
.
11111111
.
11111111
.
1
0000000

0s hide the
host

1s hide the

Breaks 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
invalid (Always)

Ex.

192.168.1.
0

255.255.255.0

OR

192.168.1.
255

255.255.255.0

Reason Behind the Rule

The all zeros host address is the same as
the network ID

Ex.

IP:

192.168.1.0

Subnet:

255.255.255.0

----------------------------------------

Network ID:

192.168.1.0

The all ones host address is reserved for

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