How large can the internet be? How many unique URLs can there possibly be on the internet?
I read this question on stackoverflow regarding the maximum limit of a URL.
The shortest URL would be x://www.x.x/ which is 12 characters long (correct me on this if I'm wrong), assuming that we disregard limitations associated with the available protocols
(http, ftp,...) and their lengths.
I also read this interesting article about how many unique sequences YouTube can have: apparently $64^{11}$ different sequences are available, of which only $0.000000000373\%$ of its potential space is being used (although the accuracy of this estimate is probably poor).
(EDIT There are a couple of limitations with this question that needs to be pointed out before this question can be answered.


*

*What characters can be used in a URL? From RFC 1738 specification:



Thus, only alphanumerics, the special characters "$-_.+!*'(),", and
  reserved characters used for their reserved purposes may be used
  unencoded within a URL.



*

*How many protocols are there? According to Wikipedia there are approximently 23 (official) network protocols. But for the sake of simplicity, we can disregard limitations associated with the available network protocols.

*How many TLDs are there? Once again the amount of domains can be disregarded aswell to keep it simple, but this list might be helpful.

*And the most relevant limitation would be the maximum length of a URL. For most of the official browsers to work, the maximum length would be < 2048. I realize it all comes down to a simple math problem now, but the question has been updated to give more details about my question.
)
Thank you all.
 A: This is not an answer but a long comment.
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&\small\verb/ Stated in current form, this question doesn't have enough /\\
&\small\verb/ technical details nailed down to have a meaningful answer. /
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Let us consider the name part of the URI.

*

*In RFC3986 -
$\small\verb/Uniform Resource Identifier (URI): Generic Syntax/$, it says


URI producers should use names that conform to the DNS syntax, even when use of DNS is not immediately apparent, and should limit these names to no more than 255 characters in length.


*

*In RFC2181 -
$\small\verb/Clarifications to the DNS Specification/$, it mentions


The DNS itself places only one restriction on the particular labels
that can be used to identify resource records.  That one restriction
relates to the length of the label and the full name.  The length of
any one label is limited to between 1 and 63 octets.  A full domain
name is limited to 255 octets (including the separators).


*

*The label part of an DNS name are not raw ASCII,
they are Punycode encoded.
Punycode is defined in RFC 3492. It is
part of the Internationalized Domain Names in Applications (IDNA) framework
to allow domain names with unicode characters representable in the ASCII character set. In particular, it means all labels beginning with xn-- are really domain names with unicode characters.
As one can see, even with only the name part, there are already so many technical details one need to nail down. This is far from a pure mathematical question.
