DNS头部

dbz0451

Which statement about DNS is true?
A. In the DNS header, the Rcode value is set to 0 for format error.
B. The client-server architecture is based on push-pull messages.
C. Query and response messages have different format.
D. In the DNS header, an Opcode value of 2 represents a server status request.
E. In the DNS message header, the QR flag set to 1 indicates a query.

A和E比较容易看出错了，其他三项呢

dingjerry

B:  没听说过DNS  push-pull message。  应该是错的。
C: DNS query and response message 的format是不一样的。
D:  对。

Opcode 2  ----    STATUS, Server status request.        RFC 1035

dingjerry

D:   STATUS, Server status request.        RFC 1035