Avaya 38DHB0002UKDD - Manual (Page 126)

Page 126 - Domain Name System (DNS) Appendix C: Overview of IP Routing
Domain Name System (DNS)
This is the system used on the Internet to match computer/host names to IP
addresses. Each host on the Internet has an IP address, rather than having to
remember these IP addresses we use names like www.sat.dundee.ac.uk to refer
to a specific host. We then send these names to a Domain Name Server which
converts the name to an IP address which the computers then use to pass data
between them.
If you wish to connect to the Internet you will need to know the IP address of the
DNS server.
Dynamic Host Configuration Protocol (DHCP)
In days of old, IP addresses were allocated to each computer/host/machine by
administrators and details recorded on paper. A protocol called Dynamic Host
Configuration Protocol (DHCP) can now do this automatically. When a computer
is switched on it sends out a broadcast on the LAN asking for an IP address, a
DHCP server will reply and allocate the machine a valid address, thus simplifying
the allocation process.
Addresses can be permanently allocated in this manner or leased for a specified
amount of time e.g. 3 days. A Windows NT computer can act as a very good and
complex DHCP server, the IPNC can act as a simple DHCP server. A major
benefit of a DHCP server is that if a PC is set for “Obtain IP address
automatically” then it can be plugged into any LAN, switched on and it will
automatically be correctly configured without any messing. There should only be
one DHCP server on any LAN.
When started (with the default configuration) the IPNC can get its IP address
from a DHCP server. If it gets no response to a request for an address, it takes
the address 192.168.42.1 and becomes a DHCP server.
By default it has 200 addresses and can thus allocate 192.168.42.2, 3, 4…198,
199, and 200. If you wish to give static addresses to other computers start at 201.
If you wish the IPNC to have an address other than 192.168.42.1 but don’t have
a DHCP server on your LAN, you need to establish communications with it by
having a PC configured with a specified IP address, e.g. 192.168.42.201 and use
that to configure the IPNC with the real IP address you wish it to have.
It is also possible to arrange for one of the existing PC’s to see network
192.168.42.0 by adding a route to it's table. Open MS-DOS prompt, enter “route”
or “route print” or “route add”.
Note: When allocating IP addresses to Dial In users the IPNC will always use
the 10M DHCP pool in preference to the 100M pool. To use the 100M
pool disable the 10M DHCP server.
Page 126 - Appendix C: Overview of IP Routing INDeX IPNC Cassette Administration Manual
Domain Name System (DNS) 38DHB0002UKDD – Issue 7 (22/11/02)