Re: Re: How to find out if PC is online

Hi, In fact you're wrong. gethostbyaddr is a DNS query tool. The host does not need to be up to be referenced in the DNS database. The dedicated tool to do that is the ICMP socket type ping

if the function responds with anything else than the IP adress then the PC must be online!

Just try: php -r "echo gethostbyname('XXX.XXX.XXX.XXX');" with an non existing ip adress. Regards, Eric At 20:10 01/12/2003, SolidDigital wrote:

What i meant to say was if gethostbyaddr(ipadress) responds with something else than the ipadress then this PC must be online. Or am I wrong?? Jocjem B.A.T. Svensson wrote:

And precisly how does the mechnaism with gethostbyaddr(), e.g. an DNS request, work to be able to resolve the issue about weather a particular host i online or not? As far as I know this is not possible. The only thing one might be able to say after a successfull DNS look up is this-or-that host has a registered entry in the DNS server. Nothing more can be deduced. If I messed something here, please fill me in. -----Original Message----- From: J.Veenhuijsen To: php-windows@lists.php.net Sent: 2003-12-01 12:53 Subject: [PHP-WIN] Re: How to find out if PC is online Try : gethostbyaddr (PHP 3, PHP 4 ) Get the Internet host name corresponding to a given IP address string gethostbyaddr (string ip_address) Returns the host name of the Internet host specified by ip_address. If an error occurs, eturns ip_address. See also gethostbyname(). Jochem Jan Hrebenar wrote:

Hello All, I`d like to make script which will detect if my computer at IP xxx.xxx.xxx.xxx is online. I try to use system("ping") but this function is not allowed on server. Can somebody tell me if exist any other way to do this? Pls excuse my english

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