...

    my $remoteIP ='a.b.c.d';
    my $port = 22; #aiming for sshd - use your own port here
    my $iaddr = inet_aton($remoteIP) || die("No $remoteIP around");
    my $paddr = sockaddr_in($port, $iaddr);
    my $protocol = getprotobyname('tcp');

    socket(SOCK, PF_INET, SOCK_STREAM, $protocol) || die("socket() fai
+led: $!");
    connect(SOCK, $paddr) || die("connect() failed: $!");
    $line = <SOCK>; #read a line 
    print("$line online\n"); #print it
    close(SOCK); #close socket

...
[download]

There are pre-built CPAN modules available that will help you connect to a variety of common servers (HTTP, SMTP, FTP, and so on).

Like any network server it don't matter.:)

A Client and a Server have to agree on certain things before they start to communicate with each other. The first is the communications protocol they'll use. (The most common these days is TCP/IP. Ten years ago it was X.25 . IBM wishs the world used SNA, which was popular 20 years ago.)

Then you both have to agree how you'll exchange information using that communications protocol. Financial institutions now use something called FIX. The Stock Exchanges used to use proprietary message formats. Then you have to worry about the character set you communicate in...

So communications prgramming is very, very specific , very detail-oriented.

For some network servers it "DO" matter ... Much to your surprise, you might discover one day not everyone is using what I suspect you assume to be universal (which I think you think it is TCP/IP). The other questions/comments make sense and my answer is an example assuming TCP ...