Đó là địa chỉ IP công cộng của bạn nhận dạng bạn trên Internet. • địa chỉ IP riêng là những người (như các địa chỉ được sử dụng trong sơ đồ trên) xác định một thiết bị trong một mạng kết nối riêng hoặc Internet. | The Benefits of DHCP Let s have a look at the settings in this example The first two lines of the configuration file instruct the DHCP server not to accept dynamic DNS-updates. The next line defines a subnet and netmask that will is used to supply the DHCP information. After that we defined all the options Option Description routers Specifies the default gateway subnet-mask Specifies the default netmask domain-name Specifies the default domain-name domain-name-servers Specifies the name-servers for our network range dynamic-bootp Specifies the range of IP addresses that the DHCP server is allowed to allocate to clients. In our example all allocated IP addresses will lie in the range . default-lease-time Defines the default lease time after which the client s DHCP configuration will expire and the client must request a new DHCP configuration from the DHCP server. In this example the DHCP lease will expire after 6 hours unless the client asks for a specific time frame. max-lease-time Defines the maximum lease allowed to the client. Note There are other options in the sample configuration file usr share doc that we won t discuss here. There s more about these options at the man page. The DHCP Lease Database How does the DHCP server keep track of the IP addresses it has leased out In Red Hat Linux 9 systems this information is stored in the database file var lib dhcp . The data stored here includes a client identifier used by the client that requested the lease the time and date of both the start and end of the lease and the address of the Ethernet network interface card that was used to retrieve the lease. Note DHCP can recognize a server by the address of its Ethernet network interface card which is unique. This address is also known as the MAC address. DHCP server stores lease information for each recently assigned IP address automatically in the lease database and you should not modify
