Home Theater Server User Manual
ServerIron ADX Global Server Load Balancing Guide 97
53-1002437-01
Transparent DNS query intercept
1
Redirecting queries
To configure transparent DNS query intercept to redirect queries to a proxy DNS server or another
GSLB ServerIron ADX:
• Configure a real server with the IP address of the proxy DNS server or other GSLB ServerIron
ADX to which you want to redirect queries.
• Configure a virtual server with the IP address of the authoritative DNS server that you want to
intercept.
• Specify the domain and host application for which you want to intercept queries.
• Configure an IP policy to enable the ServerIron ADX to examine incoming DNS packets.
NOTE
In standard GSLB configuration, the ServerIron ADX sends a DNS query to the DNS server to get the
IP addresses for the domain and performs health-checks on them. However in this transparent
intercept mode, where you do not do GSLB on the DNS response, the ServerIron ADX does not do
these things.
NOTE
The ServerIron ADX intercepts queries only for domain names configured on the ServerIron ADX. For
domain names that are not configured on the ServerIron ADX, the ServerIron ADX still sends queries
to the authoritative DNS server.
DNS
DNS
Authoritative DNS server
for domain brocade.com
209.157.23.130
proxy DNS
Alternative (proxy) DNS
209.200.22.100
SI
ServerIron configured to
intercept DNS queries to
209.157.23.130
Source IP address
209.157.23.100
3. If ServerIron redirects client query to
the proxy DNS server, the DNS server
sends response back to the
ServerIron, to the configured source IP
address.
5. Client receives response. Source
address of response is the authoritative
DNS server.
The ServerIron’s redirection or
interception is transparent to the client.
1. Client’s local DNS server
sends a recursive query for
brocade.com.
2. ServerIron either redirects client
query to the proxy DNS server, or
intercepts and directly responds to the
query.
Whether the ServerIron redirects or
directly responds to query depends on
transparent DNS configuration.
4. ServerIron changes the source
address in the reply to the authoritative
DNS server.
If the reply is from a proxy DNS server,
the ServerIron also changes the
destination address from the
ServerIron’s source IP address to the
client’s IP address.