If the FQDN's IP is cached you will get timeouts when there is no network connection. A DNS cache entry is valid until TTL is exceeded. If the DNS cache entry is stale or not cached then you will get "unknown host" when there is no network connection.
I check the network availability in my mobile apps by: 1) Set the network timeout to 2 seconds. 2) Send an https request to a webpage that calls an LC server script. 3) If there is a network connection then script returns turns an LC array with the "Status" key value of "OK". I set the app to "Network Available". 4) If there is a timeout I set the app to "Network Not Available". 5) Set the network timeout back to the previous value. I don't check the tsNet error to find out why the "ping" failed. I have a timer set to check if the network is up periodically. Ralph DiMola IT Director Evergreen Information Services rdim...@evergreeninfo.net -----Original Message----- From: use-livecode [mailto:use-livecode-boun...@lists.runrev.com] On Behalf Of Bob Sneidar via use-livecode Sent: Friday, March 02, 2018 3:02 PM To: How to use LiveCode Cc: Bob Sneidar Subject: Re: Internet checking? Yes, trying to figure out WHY the connection failed is trickier. I think you are right that Safari pings an IP (to exclude DNS problems) and then looks at the response. A ping that has no route will report something like Destination Unreachable as opposed to timeout. On my Apple terminal, if I ping a bogus DNS name, I get cannot resolve <hostname>: unknown host. If I ping a bogus IP, I get a timeout. If I disable all network adapters I get a timeout AND sendto: No route to host. Windows probably does something similar. I suppose you could simply ping through a shell and then peruse the responses. Bob S > On Mar 2, 2018, at 10:09 , Graham Samuel via use-livecode > <use-livecode@lists.runrev.com> wrote: > > Bob of course you’re right - in my particular case, anyway, I just want to > know if I can access me chosen server or not. > > But one could certainly imagine programs that would want to know if they were > wasting their time offering their users a broader internet access - I mean > any program that allows the user to specify addresses (like a browser does) > would want more of an “is there or isn’t there?” approach. On my Mac, the > Apple browser Safari can announce “you are not connected to the internet”. > Maybe it just pings a trusted source and waits for a reasonable time for the > reaction. > > Anyway what I noticed in my little experiment was that the reaction of the > script when the internet wasn’t available was very rapid (certainly less than > half a second), which means that just trying to get the file and then looking > for an error response would probably be OK for a human user, since there is > no prolonged wait. > > As you see, I am reluctant to do anything that’s at all complicated! > > Graham _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
