FQDN

[Simon Waters]

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phaniraj ranganath wrote:
>
> I want to know why the FQDN cann't be more than 256 characters
> & the name at any node in Internet Domain name space cann't be more
> than 63 characters?

The length limit is 255 not 256 I believe.

The reason is that rfc1034 says so, read the rfc's for more background,
but it says "to ease implementation".

> Is there any restriction in the number of levels
> in Internet i.e. from root servers how many levels can the structure
> of internet span?

As far as I know only the implied limit from the length restrictions
which I make 128 labels of one character.

However you would need to check the resolution algorithms to see if this
would break the resolvers in common use, as I suspect some might give up
before they had got to resolving a name involving substantially more
levels than possible. It is possible one of the RFCs implies a lower limit.

The names with most labels I've seen in use are inverse queries for IPv6
addresses, however these are broken into chunks, and so don't have
anywhere near as many levels of delegation as appearances might suggest.
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