Distech Controls ECLYPSE APEX, Руководство пользователя

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17 ECLYPSE APEX
The first IP Address is the Network ID. Networks with different network IDs are considered to be dis-
tinct. By default, no direct communication can take place between two networks that have different
Network IDs. This prevents computers on one network from being accessed by computers on another
network. When one department or organization is on one network, it is segregated from computers on
other networks.
Last IP Address is the Broadcast Address: this is used for a specific type of network traffic that is des-
tined to every host in the subnetwork range of IP addresses. For example, the device’s DHCP client
uses the broadcast address to find the network’s DHCP server.
For Example, with a typical class C private network:
Subnetwork Mask = 255.255.255.0
Network ID = 192.168.1.0
Gateway = 192.168.1.1
Broadcast Address = 192.168.1.255
Usable IP Addresses = 192.168.1.2 - 192.168.1.254
Default Gateway
Two hosts on the same subnetwork can directly communicate with each other. When a host wants to
communicate to an IP address that is not in the subnetwork address range, the host sends the packet
to the default gateway. The default gateway is usually the router’s IP address and is usually set in the
routers administration interface. For more information about IP routing, see
About Routers, Switches,
and Hubs .
Certain ECLYPSE controller services use the default gateway. See ECLYPSE Services that Require In-
ternet Connectivity .
Domain Name System (DNS)
When you want to connect to another computer or service on the Internet (to a Website for example),
rarely would you want to use the IP address to make the connection as it would be a pain to remem-
ber the numeric IP address for each and every site you want to visit. The Domain Name System
(DNS) was created to allow internet users to take advantage of a meaningful Uniform Resource Loca-
tor (URL) such as
http://www.distech-controls.com/ to connect to an IP address without having to know
the server’s or computer’s numerical IP address. The DNS does this by looking up the URL and pro-
viding the numeric IP address to the requesting computer. Should the IP address of a computer/server
be changed, the DNS server can be updated with its new IP address, thereby ensuring that other net-
worked computers can still find this computer/server through its URL.
Set the DNS IP address of the Domain Name System (DNS) servers in routers and in IP controllers
that have manually-configured IP parameters. Between one and three DNS IP address is usually pro-
vided by the Internet Service Provider (ISP). The second and third DNS addresses are for failover
should the first DNS become unavailable.
If you do not know the address of your DNS server(s), try the following publicly-available DNS server
addresses: primary = 8.8.8.8 and secondary = 4.4.4.4
Some ECLYPSE controller services use DNS to resolve Web addresses thereby allowing the service
to operate. See
ECLYPSE Services that Require Internet Connectivity .
IPv4 Communication Fundamentals