P-660R-D Series User’s Guide
2
Appendix E IP Addresses and Subnetting
An IP address with host IDs of all zeros is the IP address of the network (192.168.1.0 for example). An IP
address with host IDs of all ones is the broadcast address for that network (192.168.1.255 for example).
Therefore, to determine the total number of hosts allowed in a network, deduct two as shown next:
• A class C address (1 host octet:
8 host bits) can have 2
8
– 2, or 254 hosts.
• A class B address (2 host octets: 16 host bits) can have 2
16
– 2, or 65534 hosts.
A class A address (3 host octets: 24 host bits) can have 2
24
– 2 hosts, or approximately 16 million hosts.
IP Address Classes and Network ID
The value of the first octet of an IP address determines the class of an address.
• Class A addresses have a
0
in the leftmost bit.
• Class B addresses have a
1
in the leftmost bit and a
0
in the next leftmost bit.
• Class C addresses start with
1 1 0
in the first three leftmost bits.
• Class D addresses begin with
1 1 1 0
. Class D addresses are used for multicasting, which is used to
send information to groups of computers.
• There is also a class E. It is reserved for future use.
The following table shows the allowed ranges for the first octet of each class. This range determines the
number of subnets you can have in a network.
Subnet Masks
A subnet mask is used to determine which bits are part of the network number, and which bits are part of
the host ID (using a logical AND operation).
A subnet mask has 32 bits. If a bit in the subnet mask is a “1” then the corresponding bit in the IP address
is part of the network number. If a bit in the subnet mask is “0” then the corresponding bit in the IP address
is part of the host ID.
Table 66
Allowed IP Address Range By Class
CLASS
ALLOWED RANGE OF FIRST OCTET (BINARY)
ALLOWED RANGE OF FIRST
OCTET (DECIMAL)
Class A
0
0000000 to
0
1111111
0 to 127
Class B
10
000000 to
10
111111
128 to 191
Class C
110
00000 to
110
11111
192 to 223
Class D
1110
0000 to
1110
1111
224 to 239
Class E
(reserved)
1111
0000 to
1111
1111
240 to 255
Summary of Contents for P-660R-D Series
Page 1: ...P 660R D Series ADSL2 Router User s Guide Version 3 40 7 2006 Edition 1...
Page 2: ......
Page 10: ...P 660R D Series User s Guide 9 Customer Support...
Page 30: ...P 660R D Series User s Guide 29 Chapter 1 Getting To Know Your ZyXEL Device...
Page 66: ...P 660R D Series User s Guide 65 Chapter 4 WAN Setup...
Page 80: ...P 660R D Series User s Guide 79 Chapter 5 LAN Setup...
Page 96: ...P 660R D Series User s Guide 95 Chapter 7 Static Route...
Page 100: ...P 660R D Series User s Guide 99 Chapter 8 Dynamic DNS Setup...
Page 110: ...P 660R D Series User s Guide 109 Chapter 9 Remote Management Configuration...
Page 122: ...P 660R D Series User s Guide 121 Chapter 10 Universal Plug and Play UPnP...
Page 128: ...P 660R D Series User s Guide 127 Chapter 11 System...
Page 134: ...P 660R D Series User s Guide 133 Chapter 12 Tools...
Page 140: ...P 660R D Series User s Guide 139 Chapter 14 Troubleshooting...
Page 160: ...P 660R D Series User s Guide 141 Appendix C Wall mounting Instructions...
Page 184: ...P 660R D Series User s Guide 8 Appendix E IP Addresses and Subnetting...
Page 186: ...P 660R D Series User s Guide 2 Appendix F Command Interpreter...
Page 192: ...P 660R D Series User s Guide 4 Appendix H Splitters and Microfilters...
