Appendix C IP Addresses and Subnetting
ZyWALL 2 Plus User’s Guide
646
Figure 461
Network Number and Host ID
How much of the IP address is the network number and how much is the host ID varies
according to the subnet mask.
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). The term “subnet” is short for “sub-
network”.
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.
The following example shows a subnet mask identifying the network number (in bold text)
and host ID of an IP address (192.168.1.2 in decimal).
By convention, subnet masks always consist of a continuous sequence of ones beginning from
the leftmost bit of the mask, followed by a continuous sequence of zeros, for a total number of
32 bits.
Subnet masks can be referred to by the size of the network number part (the bits with a “1”
value). For example, an “8-bit mask” means that the first 8 bits of the mask are ones and the
remaining 24 bits are zeroes.
Table 227
IP Address Network Number and Host ID Example
1ST
OCTET:
(192)
2ND
OCTET:
(168)
3RD
OCTET:
(1)
4TH OCTET
(2)
IP Address (Binary)
11000000
10101000
00000001
00000010
Subnet Mask (Binary)
11111111
11111111
11111111
00000000
Network Number
11000000
10101000
00000001
Host ID
00000010
Содержание ADSL 2+ Security Gateway
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Страница 25: ...Table of Contents ZyWALL 2 Plus User s Guide 25 Index 679 ...
Страница 26: ...Table of Contents ZyWALL 2 Plus User s Guide 26 ...
Страница 46: ...46 ...
Страница 88: ...Chapter 3 Wizard Setup ZyWALL 2 Plus User s Guide 88 ...
Страница 131: ...131 PART II Network LAN Screens 133 Bridge Screens 145 WAN Screens 151 DMZ Screens 171 Wireless LAN 181 ...
Страница 132: ...132 ...
Страница 144: ...Chapter 6 LAN Screens ZyWALL 2 Plus User s Guide 144 ...
Страница 180: ...Chapter 9 DMZ Screens ZyWALL 2 Plus User s Guide 180 ...
Страница 190: ...190 ...
Страница 209: ...Chapter 11 Firewall ZyWALL 2 Plus User s Guide 209 Figure 138 SECURITY FIREWALL Rule Summary Edit ...
Страница 221: ...Chapter 11 Firewall ZyWALL 2 Plus User s Guide 221 Figure 149 My Service Firewall Rule Example Rule Summary Completed ...
Страница 222: ...Chapter 11 Firewall ZyWALL 2 Plus User s Guide 222 ...
Страница 252: ...Chapter 13 Content Filtering Reports ZyWALL 2 Plus User s Guide 252 ...
Страница 265: ...Chapter 14 IPSec VPN ZyWALL 2 Plus User s Guide 265 Figure 178 SECURITY VPN VPN Rules IKE Edit Gateway Policy ...
Страница 274: ...Chapter 14 IPSec VPN ZyWALL 2 Plus User s Guide 274 Figure 181 SECURITY VPN VPN Rules IKE Edit Network Policy ...
Страница 306: ...Chapter 15 Certificates ZyWALL 2 Plus User s Guide 306 Figure 203 SECURITY CERTIFICATES My Certificates Create Basic ...
Страница 328: ...Chapter 16 Authentication Server ZyWALL 2 Plus User s Guide 328 ...
Страница 330: ...330 ...
Страница 346: ...Chapter 17 Network Address Translation NAT ZyWALL 2 Plus User s Guide 346 ...
Страница 350: ...Chapter 18 Static Route ZyWALL 2 Plus User s Guide 350 ...
Страница 398: ...Chapter 21 Remote Management ZyWALL 2 Plus User s Guide 398 ...
Страница 416: ...Chapter 24 ALG Screen ZyWALL 2 Plus User s Guide 416 ...
Страница 417: ...417 PART V Logs and Maintenance Logs Screens 419 Maintenance 447 ...
Страница 418: ...418 ...
Страница 423: ...Chapter 25 Logs Screens ZyWALL 2 Plus User s Guide 423 Figure 274 LOGS Log Settings ...
Страница 466: ...466 ...
Страница 474: ...Chapter 27 Introducing the SMT ZyWALL 2 Plus User s Guide 474 ...
Страница 496: ...Chapter 30 LAN Setup ZyWALL 2 Plus User s Guide 496 ...
Страница 504: ...Chapter 32 DMZ Setup ZyWALL 2 Plus User s Guide 504 ...
Страница 508: ...Chapter 33 Wireless Setup ZyWALL 2 Plus User s Guide 508 ...
Страница 556: ...Chapter 38 Filter Configuration ZyWALL 2 Plus User s Guide 556 ...
Страница 570: ...Chapter 40 System Information Diagnosis ZyWALL 2 Plus User s Guide 570 ...
Страница 586: ...Chapter 41 Firmware and Configuration File Maintenance ZyWALL 2 Plus User s Guide 586 ...
Страница 594: ...Chapter 42 System Maintenance Menus 8 to 10 ZyWALL 2 Plus User s Guide 594 ...
Страница 598: ...Chapter 43 Remote Management ZyWALL 2 Plus User s Guide 598 ...
Страница 603: ...603 PART VII Troubleshooting and Specifications Troubleshooting 605 Product Specifications 613 ...
Страница 604: ...604 ...
Страница 612: ...Chapter 45 Troubleshooting ZyWALL 2 Plus User s Guide 612 ...
Страница 620: ...620 ...
Страница 644: ...Appendix B Pop up Windows JavaScripts and Java Permissions ZyWALL 2 Plus User s Guide 644 ...
Страница 668: ...Appendix E Importing Certificates ZyWALL 2 Plus User s Guide 668 ...
Страница 672: ...Appendix F Legal Information ZyWALL 2 Plus User s Guide 672 ...
Страница 678: ...Appendix G Customer Support ZyWALL 2 Plus User s Guide 678 ...