Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 80)

70 Brocade Virtual ADX Global Server Load Balancing Guide
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Transparent DNS query intercept
1
NOTE
A Brocade Virtual ADX configured for transparent intercept redirects or directly responds to client
requests only for domain configured on the Brocade Virtual ADX. If the domain name requested by
the client is not configured on the Brocade Virtual ADX, it forwards the query to the actual DNS server
without intercepting, and the reply is untouched by GSLB.
Example
Figure 5 shows an example of a configuration that uses transparent DNS query intercept. In this
example, the Brocade Virtual ADX is configured to intercept all client queries to the zone
brocade.com and redirect them to the proxy DNS server and apply GSLB on the reply. The Brocade
Virtual ADX uses its configured source-ip to make sure the DNS reply from the proxy server comes
to it.
• The client’s local DNS server sends a recursive query for brocade.com to the authoritative DNS
server (10.157.23.130).
• The Brocade Virtual ADX intercepts and redirects client query to proxy DNS server
(10.200.22.100).
• The proxy DNS server sends response back to the Brocade Virtual ADX’s source IP address
(10.157.23.100).
• The Brocade Virtual ADX changes the source address in the reply to the authoritative DNS
server’s address and the destination address from the Brocade Virtual ADX’s source-IP to the
client’s IP address.
• The client receives the DNS response with the authoritative DNS server’s source IP address.
The Brocade Virtual ADX’s interception and redirection is transparent to the client.