The IAB reached the same conclusion that the ICANN Security and Stability Advisory Committee (SSAC) came to last February. The SSAC's report was one of the sources used for the IAB's advisory.
"Dotless domains will not be universally reachable and the SSAC recommends strongly against their use," the SSAC concluded in its report at the time.
Sending email to dotless domains would be a problem because, for example, standard-compliant mail servers would reject messages to addresses such as user@brand, the SSAC said.
The SSAC also warned of security risks: "For example, until very recently most Certificate Authorities would issue a Hypertext Transfer Protocol Secure (HTTPS) certificate for any dotless hostname with no validation (under the assumption that such hostnames, by definition, were not globally reachable). If dotless domains are allowed, these historical Certificate Authority Issuance practices pose a significant security risk to the privacy and integrity of HTTPS communications," the SSAC warned.
In its own memo, dated July 13, the IETF concluded that implementations of application protocols can exhibit unexpected behavior in processing dotless domains.
Dotless domains also do not fit "within the rule of least surprise," the IETF said. "The rule of least surprise is a principle which states that it is better to always do the less surprising thing," it said.
The IETF however only looks at technical mechanisms. Whether dotless domains are harmful is a policy matter, the IETF said in the memo.
The memo is also an Internet Draft document that expires in January 2014. Internet Drafts are IETF working documents that are valid for a maximum of six months and may be updated, replaced, or made obsolete by other documents at any time, so they must be seen as a "work in progress," the IETF said.
A Google spokesman reached on Monday did not immediately respond to a request for comment.
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