Nortel BCM 3.7, Manual

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Programming Operations Guide
Chapter 32
Configuring DNS
Business Communications Manager functions as both a gateway to the Internet and as a DNS
proxy.
When Business Communications Manager receives DNS requests from clients, it first checks its
local cache for name entries and records. If found locally, Business Communications Manager
immediately responds to clients. Otherwise, Business Communications Manager creates a new
DNS request to the remote Primary or Secondary DNS servers on behalf of the client. If the remote
DNS server responds with the requested records, they are forwarded to clients and cached in
Business Communications Manager. By caching the DNS requests, the DNS proxy service on
Business Communications Manager reduces the number of external DNS requests and thus
reduces the amount of WAN traffic.
The DNS proxy service also provides additional security. When DNS requests are sent to the
Primary or Secondary DNS servers, the Business Communications Manager internal IP address is
used for the request. By using the Business Communications Manager IP address, the IP addresses
of the internal users can remain hidden.
Note: If your PC is a DHCP client under Business Communications Manager, you do not
have to let your workstations know that Business Communications Manager is your
Internet gateway.
Note: If you use the Quick Install Wizard, DNS proxy is enabled by the wizard.