dns - 缓存名称服务器是否通常缓存否定的 DNS 响应 SERVFAIL

Question

缓存名称服务器是否通常缓存否定的 DNS 响应 SERVFAIL？

编辑:
为了澄清这个问题，我可以看到缓存名称服务器缓存否定响应 NXDOMAIN、NODATA。但它不会为 SERVFAIL 响应执行此操作。这是故意的吗？

Answer 1

SERVFAIL 包含在 RFC2308 的 §7.1 中:

Server failures fall into two major classes. The first is where a server can determine that it has been misconfigured for a zone. This may be where it has been listed as a server, but not configured to be a server for the zone, or where it has been configured to be a server for the zone, but cannot obtain the zone data for some reason. This can occur either because the zone file does not exist or contains errors, or because another server from which the zone should have been available either did not respond or was unable or unwilling to supply the zone.

The second class is where the server needs to obtain an answer from elsewhere, but is unable to do so, due to network failures, other servers that don't reply, or return server failure errors, or similar.

In either case a resolver MAY cache a server failure response. If it does so it MUST NOT cache it for longer than five (5) minutes, and it MUST be cached against the specific query tuple <query name, type, class, server IP address>.

所以基本上，它取决于您的名称服务器的实现。