Brocade Communications Systems 12.4.00 Applying Gslb to Cname records, Syntax no dns cname-detect

1 Proxy for DNS server

•IMAP4: the well-known name for port 143

•LDAP: the well-known name for port 389

•NNTP: the well-known name for port 119

•POP3: the well-known name for port 110

•SMTP: the well-known name for port 25

•TELNET: the well-known name for port 23

The <TCP/UDP-port-num>parameter specifies a TCP/UDP port number instead of a well-known port. If the application is not one of those listed above, you still can configure the GSLB ServerIron ADX to perform the Layer 4 health check on the specified port. If the application number does not correspond to one of the well-known ports recognized by the ServerIron ADX, the GSLB ServerIron ADX performs Layer 4 TCP or UDP health checks for the ports but does not perform application-specific health checks.

Applying GSLB to CNAME records

A Canonical Name (CNAME) record is a type of DNS record that allows network administrators to create aliases for domain names. For example, an administrator can create the following DNS records for the Brocade domain:

•Address record: www.brocade.com, IP address 209.157.22.241

•CNAME record: www.brocade.com, alias for www.brocade.com

A CNAME record refers to another domain name instead of an IP address. A client can enter either domain name to get to the site. In this example, each domain name goes to site 209.157.22.241.

GSLB supports CNAME records. If you configure domain names that map to other domain names, the GSLB ServerIron ADX still will perform GSLB for the domain.

By default, the ServerIron ADX applies the GSLB policy only to zone and application names that are configured on the ServerIron ADX. Thus, if the ServerIron ADX receives a DNS reply that contains CNAME records for the requested zone and application, the ServerIron ADX does not apply the GSLB policy to the CNAME records.

You can enable the ServerIron ADX to search its GSLB database for the zone and application names in CNAME records. For example, if the ServerIron ADX receives a DNS reply that contains the CNAME record www.brocade.com, and the zone and application name "www.brocade.com" have been configured on the ServerIron ADX, the ServerIron ADX will apply the GSLB policy to the CNAME record.

To enable the ServerIron ADX to apply GSLB to CNAME records, enter the following commands.

ServerIronADX(config)# gslb policy

ServerIronADX(config-gslb-policy)# dns cname-detect

Syntax: [no] dns cname-detect

NOTE

This feature does not apply to cache proxy GSLB or transparent intercept GSLB.

22	ServerIron ADX Global Server Load Balancing Guide
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