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CHAPTER 4
Raven EDGE/GPRS for Cingular - User Guide, version 2.31
IP Manager and DNS
If you have a fleet of AirLink modems or even if you only have one, it can be difficult to keep track
of the current IP addresses, especially if the addresses aren't static but change every time the
modem connects to Cingular. If you need to connect to the modem, or the device behind it, it is so
much easier to connect when you have a name (car54.mydomain.com, where are you?).
Reasons to contact the modem and/or the connected device:
•
Requesting a location update from a delivery truck.
•
Contacting a surveillance camera to survey the area.
•
Remote access to a computer.
•
An oil derek that needs to be triggered to begin pumping.
•
Sending text to be displayed by a road sign.
•
Monitoring the status of a remote modem.
Domain names, though, are often only connected to static IP addresses because of the way most
domain name (DNS) servers are set-up. Dynamic DNS servers require notification of IP Address
changes so they can update their DNS records and link a dynamic IP address to the correct name.
Since many cellular providers, like wire-based ISPs, do not offer static IP addresses or static
address accounts cost a premium vs. dynamic accounts, IP Manager was developed to work with a
Dynamic DNS server to receive notification from AirLink modems to translate the modem's
dynamic IP address to a fully qualified domain name. Thus, you can contact your Raven directly
from the Internet using a domain name.
•
Dynamic IP addresses are granted only when your Raven is connected and can change each
time the modem reconnects to the network.
•
Static IP addresses are granted the same address every time your Raven is connected and are not
in use when your Raven is not connected.
A dynamic IP address is suitable for many Internet activities such as web browsing, looking up data
on another computer system, data only being sent out, or data only being received after an initial
request. However, if you need to contact your Raven directly, a device connected to the modem, or
a host system using your Raven, a dynamic IP won't give you a reliable address to contact (since it
may have changed since the last time it was assigned).
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