Rcode Field - Wiznet W5100E01-AVR User Manual

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dns_parse_response() of <Fig 3.42> analyzes Response Message received by DNS Name Server.

dns_parse_response() checks if it's same as Request Message ID that was sent to DNS Name Server and it

also checks if the message received is a response message by checking QR Field of Header Section. If the

received message is response from DNS Name Server, the success of change is decided by checking the

RCODE Field value of Header Section.

<Table 3-42> is definition of constants that are used in RCODE Field.

Definition

#define RC_NO_ERROR

#define RC_FORMAT_ERROR

#define RC_SERVER_FAIL

#define RC_NAME_ERROR

#define RC_NOT_IMPL 4

#define RC_REFUSED

If the RCODE is RC_NO_ERROR, variable length sections such as Question, Answer, Authority, and

Additional Section are analyzed. Since the necessary information is set in Answer Section, it's analyzed and

processed, and other section analysis and process are not performed. If you need information on Authority

and Additional Section, you can get them easily on your own.

Question Section is processed as many as QDCOUNT of Header Section by calling dns_parse_question().

Answer Section is processed as many as ANCOUNT of Header Section by calling dns_parse_question().

No error condition

Format error - The name server was unable to interpret

the query

Server failure - The name server was unable to process

this query due to a problem with the name server

Name Error - Meaningful only for responses from an

authoritative name server, this code signifies that the

domain name referenced in the query does not exist.

Not Implemented - The name server does not support

the requested kind of query.

Refused - The name server refuses to perform the

specified operation for policy reasons.

Description

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