what's a valid domain name?

[John Wobus]

So 10.14.22.11 is a legal hostname, right?

We had a recent experience where our DNS administration
system allowed someone to insert in a CNAME record that
resembled this:

www.example.com. CNAME 10.14.22.11.

A fascinating thing about this is that my computer/browser could
take me to www.example.com just fine.

John Wobus
Cornell



On Jan 30, 2011, at 7:30 AM, pyh at mail.nsbeta.info wrote:

>
> From RFC 1123
>
>        One aspect of host name syntax is hereby changed: the
>        restriction on the first character is relaxed to allow either a
>        letter or a digit.  Host software MUST support this more  
> liberal
>        syntax.
>
>
>
>
> pyh at mail.nsbeta.info writes:
>
>> Joseph S D Yao writes:
>>
>>>
>>> The labels must follow the rules for ARPANET host names.  They must
>>> start with a letter, end with a letter or digit, and have as  
>>> interior
>>> characters only letters, digits, and hyphen.  There are also some
>>> restrictions on the length.  Labels must be 63 characters or less.
>>>
>>
>> A label must start with a letter? oh I don't think so.
>> How about these domains which all have huge DNS traffic?
>>
>> 163.com
>> 126.com
>> 51.com
>> 56.com
>>
>> yes 163.com is a domain name but "163" also can be treated as a  
>> label for
>> domain "com.", is it?
>>
>> Thanks.
>>
>> Regards.
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