Supported characters in a host name

[surendar prabu]

I am using javax.net API to make a connection to a remote server. I dont want to use the IP address but only the host name. Is there any characters that are not supported by the API , which I have to avoid while naming my server?

regards,
Surendar Prabu

[Nicholas Jordan]

/* RFC2396 specifies precisely which characters are permitted in the
 * various components of a URI reference.  The following categories, most of
 * which are taken from that specification, are used below to describe these
 * constraints:
 *
 * 
 *   alpha
 *       The US-ASCII alphabetic characters,
 *    'A'through'Z'
 *    and 'a'through'z'
 *   digit
 *       The US-ASCII decimal digit characters,
 *       '0'through'9'
 *   alphanum
 *       All alpha and digit characters
 *   unreserved
 *       All alphanum characters together with those in the string
 *    "_-!.~'()*"
 *   punct
 *       The characters in the string ",;:$&+="
 *   reserved
 *       All punct characters together with those in the string
 *    "?/[]@"
 *   escaped
 *       Escaped octets, that is, triplets consisting of the percent
 *           character ('%') followed by two hexadecimal digits
 *           ('0'-'9', 'A'-'F', and
 *           'a'-'f')
 *   other
 *       The Unicode characters that are not in the US-ASCII character set,
 *           are not control characters (according to the {@link
 *           java.lang.Character#isISOControl(char) Character.isISOControl}
 *       method), and are not space characters (according to the {@link
 *       java.lang.Character#isSpaceChar(char) Character.isSpaceChar}
 *       method)(Deviation from RFC 2396, which is
 *       limited to US-ASCII)
 */