Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 103)

ServerIron ADX Global Server Load Balancing Guide 91
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DNS cache proxy
1
TCP APP Count (%)
* 1.1.1.16: cfg real-ip ACTIVE N-AM 5 17 0 (0%)
* 1.1.1.108: cfg v-ip ACTIVE N-AM 0 0 5 (100%)
show gslb dns detail
Use this command to display the affinity group associated with the domain and the number of
selections based on affinity.
Syntax: show gslb dns detail []
ServerIronADX# show gslb dns detail
ZONE: foo.com
HOST: www:
(Global GSLB policy)
GSLB affinity group: 7
Flashback DNS resp.
delay selection
(x100us) counters
TCP APP Count (%)
* 1.1.1.16: cfg real-ip ACTIVE N-AM 5 15 0 (0%)
* 1.1.1.108: cfg v-ip ACTIVE N-AM 0 0 5 (100%)
Active Bindings: 1
site: local, weight: 0, SI: 1.1.1.102
session util: 0%, avail. sessions: 1999996
preference: 128
Metric counter (count [selection-metric]):
No metric count yet
Affinity selection count = 5
Debug command
Use the following command to enable debugging for domain-level affinity.
ServerIronADX(config)# gslb trace 10
Syntax: gslb trace [| ]
DNS cache proxy
The DNS cache proxy feature allows the ServerIron ADX to act as a proxy for a DNS server by
responding directly to the client queries without forwarding them to the DNS server. Just as in the
GSLB DNS proxy mode, the ServerIron ADX periodically queries the authoritative DNS server for IP
addresses corresponding to the domains configured for GSLB and caches them. However, unlike
GSLB DNS proxy, the ServerIron ADX does not forward every client query to the authoritative DNS
server, it responds directly to the client using the cached address list for the requested domain.
When you enable DNS cache proxy, the ServerIron ADX applies the GSLB policy to the IP addresses
it has cached for the requested domain, and responds to the client with the best address. The
ServerIron ADX refreshes the address cache by periodically querying the authoritative DNS server.
The default update interval is 30 seconds and is configurable.
The DNS cache proxy feature is useful in network environments where the traffic between the
ServerIron ADX and the authoritative DNS server introduces noticeable latency in the response to
client requests. For example, if the ServerIron ADX and the authoritative DNS server are connected
over the Internet, this feature can eliminate the delays caused by that connection.