Potential pitfalls in DNS handling
Posted Nov 15, 2012 20:10 UTC (Thu) by bjencks
In reply to: Potential pitfalls in DNS handling
Parent article: Potential pitfalls in DNS handling
Further up 2.3.1 it says:
"For example, when naming a mail domain, the user should satisfy both the rules of this memo and those in RFC-822. When creating a new host name, the old rules for HOSTS.TXT should be followed. This avoids problems when old software is converted to use domain names.
The following syntax will result in fewer problems with many applications that use domain names (e.g., mail, TELNET)."
and proceeds to describe the rules you quoted, indicating that those rules are guidelines for maximum interoperability, not MUST specifications of the protocol.
Section 3.1 reinforces this:
"Although labels can contain any 8 bit values in octets that make up a label, it is strongly recommended that labels follow the preferred syntax described elsewhere in this memo, which is compatible with existing host naming conventions."
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