INTERNET ADDRESSING
ICANN International
Corporation of Assigned Names and Numbers.
A private, nongovernment organization that ensures each user has a
unique IP address.
Decimal: Each quad with a
value between 0 (binary 0~field off) and 255 (binary 1~field on)
INTERNET ADDRESS CLASSES
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Class |
1st byte |
1st bit(s) |
Network/Host Portions
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A |
1-126 |
0 |
8 bits/1
byte 126 networks |
24 bits/3
bytes 16,777,214
hosts |
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0.0.0.0 to
127.255.255.255 |
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0.0.0.0 |
Used when computer initializes and
requests an IP address. Source
address is initially 0.0.0.0 until it is assigned an IP address
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10.0.0.0 to
10.255.255.255 |
Reserved IP addressing for private
internets
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127 loopback:
Cannot be used as internet address.
Allows client/server on same host to communicate. Ideal for testing/troubleshooting
(127.0.0.1 localhost) |
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B |
128-191 |
10 |
16 bits/2
bytes 16,384
networks |
16 bits/2
bytes 65,534 hosts |
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128.0.0.0 to
191.255.255.255 |
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172.16.0.0
to 172.31.255.255 |
Reserved IP addressing for private
internets
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C |
192-223 |
110 |
24 bits/3
bytes 2,097,152
networks |
8 bits/1
byte 254 hosts |
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192.0.0.0 to
223.255.255.255 |
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192.168.0.0 to 192.168.255.255 |
Reserved IP addressing for private internets
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D |
224-239 |
1110 |
MULTICASTING: Not
routable. Datagram targeted to a
group that is identified by network address only. (no host portion)
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224.0.0.0 to
239.255.255.255 |
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E |
240-247 |
11110 |
EXPERIMENTAL: Reserved for future use. |
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240.0.0.0 to
247.255.255.255 |
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BROADCAST ADDRESSES (255) (Network and host portions cannot be 255)Send
messages to all network hosts and are used only as destination addresses. |
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Limited Broadcast255.255.255.255 |
Used
for configuring hosts when they boot up.
(Not valid for sending and receiving)
Can broadcast to obtain an IP address from DHCP or BOOTP servers. |
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Net-directed
Broadcast |
Used
to broadcast to all hosts in a network. Assigned network quad(s) host quad(s)
is/are 255 |
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Subnet-directed
Broadcast |
Broadcast
can be sent to all hosts within a subnet. |
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All-subnets-directed
Broadcast |
Has
become obsolete ~ multicasting is preferred.
Broadcast can be sent to all hosts within all network subnets. |
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