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Chapter 4. Your Internet Service Provider (ISP)
Your ISP is your connection to the Internet - it routes Internet data packets to and from your server. It also provides other essential
services. This section of the user’s guide reviews what ISPs offer and what the implications are in choosing among the various
options available to you. While your ISP can also assist you in selecting and arranging the right Internet services for your
organization, it’s important to know the general range of services available, since not all ISPs offer all services.
Warning
If you are operating the product in "server-only" mode, you will need to review your gateway/firewall documentation and
perhaps consult with your ISP regarding your configuration. For example, depending on your plans for the server, your
ISP may need to publish DNS records associating your mail and/or web servers with your firewall IP address. You may
also need to configure your firewall for port forwarding of services.
In server-only mode, the single Ethernet connection to the local network is "trusted" as being secure and packet filtering
is disabled. For that reason, a server-only server must always be behind a local firewall. You should not directly connect
such a system to the Internet via an Internet Service Provider.
4.1. Dedicated versus dialup connectivity
Connectivity, also referred to as Internet access type, refers to the physical connection between your site and your ISP. How you
connect to your ISP affects the speed of your Internet connection, which, in turn, impacts such things as how quickly your web site is
displayed to visitors.
Dedicated connectivity refers to a full-time connection to your ISP. Although they are more expensive than the alternative, dedicated
connections are generally faster and allow you to use the full range of services on your server. There are several common types of
dedicated connectivity. ADSL provides relatively fast data transmission over phone lines. A cable connection links you to your
cable company, which provides you with many (though not all) of the same services as a traditional ISP. The speed of transmission
over a cable network can vary widely (from quite fast to very slow) based in part on the usage within your neighborhood.
If you have dialup connectivity, your server is not permanently connected to the Internet. Rather, it connects to your ISP over a
phone line using a modem. Because your connection to the Internet is not permanent, some of the services on your server cannot be
provided to the outside world. For example, having your server host your external company web site would create a problem because
whenever your server was not connected to the Internet, the web site would not be available. (However, it could certainly host an
intranet web site because the local network would always be connected.)
4.2. The IP address
An IP address is an identifying number assigned to all devices connected to the Internet, and is used in routing information from one
device to another. Like your phone number, your IP address enables other people to reach you. In our standard configuration, your
ISP only needs to allocate one IP address for your network. It is assigned to your server, which will accept all the Internet data
packets intended for your network and distribute them to the appropriate computer - much like an office receptionist is able to accept
incoming calls and direct them to the appropriate extension.
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