## page was renamed from DNS/NXDOMAIN/DJBの見解
== DNS/NXDOMAIN/DJBの見解 ==

NXDOMAIN返答対象ドメイン名より下の部分についてはこのような議論がある。
  [[DNS/RFC/8020]] が認められる前まで。

http://cr-yp-to.996295.n3.nabble.com/Fixing-the-NXDOMAIN-NODATA-bug-in-tinydns-td17150.html#a17171

Returning NXDOMAIN for empty nonterminals is not a bug.

It is perfectly interoperable behavior that has been used and continues to be used by
many different pieces of DNS software, including many versions of BIND.

The behavior has never caused problems for DNS users.

Fun historical fact: This behavior was put into the first version of
tinydns after a public statement by BIND maintainer Paul Vixie saying
that this behavior is _required_. Here's the exact Vixie quote:

   RFC 2308 implicitly outlawed BIND's behaviour, which is to return
   NOERROR/ANCOUNT=0 for empty nonterminals. After RFC 2308, empty
   nonterminals are signalled with NXDOMAIN.

[[/続き]]

== 参考 ==
Notes on the Domain Name System
http://cr.yp.to/djbdns/notes.html

The five types of DNS responses
  1. CNAME返答(qtypeはCNAMEでないとき。RCODEには関係しない。）
  2. NXDOMAIN(RCODE=3) 1.に該当しないもの。
  3. 該当レコードあり。
  4. delegation
  5. NoData返答 (1から4に該当しない）