Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 202)

190 ServerIron ADX Global Server Load Balancing Guide
53-1002437-01
GSLB error handling for unsupported DNS requests
1
Error handling response format
The GSLB error handling response format complies with RFC 2308, NODATA type 3 response. By
default, the return code (rcode) is noerror. The RFC 2308 format is as follows.
NO DATA RESPONSE: TYPE 3
Header:

RDCODE=NOERROR

Query:

ANOTHER.EXAMPLE.A

Answer:

<empty>

Authority:

<empty>

Additional:

<empty>
The above is an authoritative answer with rcode=NOERROR, answer=0, and no Start of Authority
(SOA) record. This error handling response prevents the client from timing out on the query and
causes the client to query for another record type instead of continuing to query for the
unsupported record type.
Although Brocade does not advise you to do so, you can configure the return code for error
handling responses. Refer to the section
“Configuring the return code” on page 190.
Disable or re-enabling GSLB error handling
GSLB error handling is enabled by default in cache proxy configurations. It is disabled by default in
transparent intercept mode.
To disable GSLB error handling, enter the following command.
GSLB-ServerIronADX(config)# gslb no-error-handling
Syntax: [no] gslb no-error-handling
To re-enable GSLB error handling, enter the following command.
GSLB-ServerIronADX(config)#no gslb no-error-handling
Configuring the return code
Although Brocade does not advise you to do so, you can configure the return code for error
handling responses, by entering a command such as the following:
GSLB-ServerIronADX(config)# gslb dns-rcode notimp
This option causes the GSLB ServerIron ADX to respond with the error code notimp (not
implemented) in the error handling response.
Syntax: [no] gslb dns-rcode [former | noerror | notimp | nxdomain | refused | servfail]
former = format error
noerror = no error (the default)
notimp = not implemented
nxdomain = non-existant domain