## page was renamed from DNS/基礎知識/TCP/は必須
## page was renamed from DNS/基礎知識/TCPは必須
## page was renamed from DNS/基礎知識/TCP
## page was renamed from DNS/用語/TCP/Introduction
## page was renamed from DNS/TCP/Introduction
DNS/TCP/Introductionについて、ここに記述してください。

Section 6.1.3.2 of [RFC1123] states:

      DNS resolvers and recursive servers MUST support UDP, and SHOULD
      support TCP, for sending (non-zone-transfer) queries.

However, some implementors have taken the text quoted above to mean
that TCP support is an optional feature of the DNS protocol.

The majority of DNS server operators already support TCP and the
default configuration for most software implementations is to support
TCP. 

The primary audience for this document is those implementors
whose failure to support TCP restricts interoperability and limits
deployment of new DNS features.

This document therefore updates the core DNS protocol specifications
such that support for TCP is henceforth a REQUIRED part of a full DNS
protocol implementation.

{{{
Whilst this document makes no specific recommendations to operators
   of DNS servers, it should be noted that failure to support TCP (or
   the blocking of DNS over TCP at the network layer) may result in
   resolution failure and/or application-level timeouts.
}}}