Brocade Communications Systems 12.4.00 Configuring DNS domain name aliases, Proxy for DNS server

1 Proxy for DNS server

Syntax: host-info<host-name> http <TCP-portnum> status-code<range> [<range> [<range> [<range>]]]

You can specify up to four ranges (total of eight values). To specify a single message code for a range, enter the code twice. For example to specify 200 only, enter the following command: port http status-code 200 200.

NOTE

When you change the status code ranges, the defaults are removed. As a result, you must specify all the valid ranges, even if a range also is within the default ranges. For example, if you still want codes 200-299 to be valid, you must specify them.

NOTE

When a URL string is associated with a TCP port number rather than the well-known HTTP port, the ServerIron ADX performs both a TCP and an HTTP health check. In this case, you must specify the method and URL before specifying the status code ranges. The software displays an error message if you accidentally try to change the status codes before specifying the method and URL.

Configuring DNS domain name aliases

You can configure an alias for a domain name and application configured on the GSLB ServerIron ADX. This feature is useful together with the DNS cache proxy feature when you want the GSLB ServerIron ADX to learn a set of proxy server IP addresses for a domain, then respond to client requests with the best proxy server address.

Typically, you use this set of features when the DNS server contains a single server address for the actual domain name, but a separate set of proxy server addresses for an alias for that domain name. When you enable DNS cache proxy and configure the alias for the domain on the GSLB ServerIron ADX, the GSLB ServerIron ADX:

•Learns the proxy server addresses under the alias on the DNS server instead of the address for the domain’s actual site. This requires configuration of the alias on the GSLB ServerIron ADX.

•Responds to client queries for the actual domain name with the best site address from among the proxy server addresses learned from the DNS server under the alias. This requires that enable the DNS cache proxy feature.

NOTE

Use this feature only in conjunction with the DNS cache proxy feature. Otherwise, it is possible for the IP address(es) the ServerIron ADX learns under the real domain name and the addresses it learns under the alias to be different. When this is the case, the ServerIron ADX does not make any alterations to the DNS response but instead sends the response back to the client unaltered. As a result, the ServerIron ADX sends the client the DNS reply with the real domain name’s server address, instead of one of the proxy addresses configured on the DNS server under the domain’s alias.

To configure an alias for a domain name, enter the alias after entering the zone name and host application names, as in the following:

ServerIronADX(config)# gslb dns zone brocade.com ServerIronADX(config-gslb-dns-brocade.com)# host www http ServerIronADX(config-gslb-dns-brocade.com)# host www alias www.gslb.brocade.com

The commands configure a zone called “brocade.com”, associate an HTTP host named “www” with the zone, then associate the alias “www.gslb.brocade.com” with the host and zone.

24	ServerIron ADX Global Server Load Balancing Guide
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