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Appendix A IP Addresses and Subnetting
149
Subnet masks are expressed in dotted decimal notation just like IP addresses. The following
examples show the binary and decimal notation for 8-bit, 16-bit, 24-bit and 29-bit subnet masks.
Network Size
The size of the network number determines the maximum number of possible hosts you can have
on your network. The larger the number of network number bits, the smaller the number of
remaining host ID bits.
An IP address with host IDs of all zeros is the IP address of the network (192.168.1.0 with a 24-bit
subnet mask, for example). An IP address with host IDs of all ones is the broadcast address for that
network (192.168.1.255 with a 24-bit subnet mask, for example).
As these two IP addresses cannot be used for individual hosts, calculate the maximum number of
possible hosts in a network as follows:
Notation
Since the mask is always a continuous number of ones beginning from the left, followed by a
continuous number of zeros for the remainder of the 32 bit mask, you can simply specify the
number of ones instead of writing the value of each octet. This is usually specified by writing a “/”
followed by the number of bits in the mask after the address.
For example, 192.1.1.0 /25 is equivalent to saying 192.1.1.0 with subnet mask 255.255.255.128.
The following table shows some possible subnet masks using both notations.
Table 60
Subnet Masks
BINARY
DECIMAL
1ST
OCTET
2ND
OCTET
3RD
OCTET
4TH OCTET
8-bit mask
11111111
00000000
00000000
00000000
255.0.0.0
16-bit mask
11111111
11111111
00000000
00000000
255.255.0.0
24-bit mask
11111111
11111111
11111111
00000000
255.255.255.0
29-bit mask
11111111
11111111
11111111
11111000
255.255.255.248
Table 61
Maximum Host Numbers
SUBNET MASK
HOST ID SIZE
MAXIMUM NUMBER OF
HOSTS
8 bits
255.0.0.0
24 bits
2
24
– 2
16777214
16 bits
255.255.0.0
16 bits
2
16
– 2
65534
24 bits
255.255.255.0
8 bits
2
8
– 2
254
29 bits
255.255.255.248
3 bits
2
3
– 2
6
Table 62
Alternative Subnet Mask Notation
SUBNET MASK
ALTERNATIVE
NOTATION
LAST OCTET
(BINARY)
LAST OCTET
(DECIMAL)
255.255.255.0
/24
0000 0000
0
255.255.255.128
/25
1000 0000
128
255.255.255.192
/26
1100 0000
192
Summary of Contents for BG-418N v1
Page 4: ...Contents Overview 4...
Page 10: ...Table of Contents 10...
Page 11: ...11 PART I User s Guide...
Page 12: ...12...
Page 20: ...Chapter 2 The Web Configurator 20...
Page 34: ...Chapter 3 Connection Wizard 34...
Page 56: ...Chapter 4 Modes 56...
Page 65: ...65 PART II Technical Reference...
Page 66: ...66...
Page 84: ...Chapter 6 Wireless LAN 84...
Page 96: ...Chapter 8 LAN 96...
Page 108: ...Chapter 10 Network Address Translation 108...
Page 118: ...Chapter 13 Remote Management 118...
Page 124: ...Chapter 14 Universal Plug and Play UPnP 124...
Page 136: ...Chapter 17 Tools 136...
Page 140: ...Chapter 19 Language 140...
Page 166: ...Appendix B Pop up Windows JavaScripts and Java Permissions 166...