Checking if a host is online

I'm creating an application for an Intranet that, among other things, is supposed to check to see if particular hosts are online, and if so, what their IP address is. Anyone know how I can accomplish this? I tried using exec("host $host"); (where $host is the hostname) and while this gets the IP it gets the IP address sometimes even if the host is not active, because a DNS record for the system still exists. I also looked into the gethostbyname() function, but that has similar problems to using the external host command. I also tried to use an external ping command (ping -c 1 $host), and while I could get that to work, since it returns non-zero status if the host can not be contacted, it takes quite a while to execute for even a few hosts at once. Anyone ever do this king=d of thing before or have any suggestions on what might work? -- Jason Giangrande <jason@giangrande.org> http://www.giangrande.org http://www.dogsiview.com

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