Microsoft windows 2000 DNS manual Primary Zone

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com.

		yyy.com.				zzz.com.			someother.com.
2			3	External world / Global Network
YYY corporation								ZZZ corporation
	Proxy Server			VPN	VPN		Firewall

	4	.
1

yyy.com.

YYY corporation

ZZZ corporation

2

zzz.com.

yyy.com. 3

first.yyy.com. second.yyy.com. third.yyy.com. first.zzz.com. second.zzz.com. third.zzz.com.

1 4

Zone.Name. Primary Zone

Zone.Name.

Secondary Zone

A DNS Server, Firewall, VPN or Proxy Server A DNS Client

Now consider an interesting case of a corporate computer that needs to resolve an external name of a computer from its own company.

A computer in the YYY Corporation needs to open a web page on the www.yyy.com. machine. Since it is a proxy client it sends a request to the proxy server (Step 1) after it finds that the name www.yyy.com. is external, based on the PAC file. The proxy server sends a DNS query to the assigned DNS server (Step 2) which happens to be authoritative for www.yyy.com. The DNS server resolves the query and returns the response to the proxy client (Step 3). Finally the proxy server uses the obtained IP address of www.yyy.com. to contact it and provides necessary info to the client (Step 4).

Windows 2000 White Paper

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