Draytek VigorSwitch G2080, Руководство пользователя, Страница: 33 / 120

VigorSwitch G2080 User’s Guide 27
Subnet mask: Subnet mask is made for the purpose to get more network
address because any IP device in a network must own its IP
address, composed of Network address and Host address,
otherwise can’t communicate with other devices each other.
But unfortunately, the network classes A, B, and C are all
too large to fit for almost all networks, hence, subnet mask is
introduced to solve this problem. Subnet mask uses some
bits from host address and makes an IP address looked
Network address, Subnet mask number and host address. It
is shown in the following figure. This reduces the total IP
number of a network able to support, by the amount of 2
power of the bit number of subnet number (2^(bit number of
subnet number)).
Subnet mask is used to set the subnet mask value, which
should be the same value as that of the other devices resided
in the same network it attaches.
For more information, please also see the Section 2-1-5 “IP
Address Assignment” in this manual.
Default: 255.255.255.0
Default gateway: Set an IP address for a gateway to handle those packets that
do not meet the routing rules predefined in the device. If a
packet does not meet the criteria for other pre-defined path,
it must be forwarded to a default router on a default path.
This means any packet with undefined IP address in the
routing table will be sent to this device unconditionally.
Default: 192.168.1.254
DNS Server You can set the DNS server by manual or auto when the
DHCP is enabled. Only manual setting is supported when
DHCP is disabled. The DNS server IP will be obtained from
DHCP server when you set the DNS server by auto.