-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 6/1/11 5:34 PM, G S wrote: > But since this test doesn't actually check the routes to these > hosts, how would it be able to provide meaningful results even in > these cases?
Note: I am _not_ an SCNetworkReachability guru, so take this all with a grain of salt. How do you know that the routes aren't tested? Quoting from your first message: "A remote host is considered reachable when a data packet, sent by an application into the network stack, can leave the local device." If the kernel cannot route the packet, this would be interpreted by any sane implementation as "cannot leave the local device." A kernel routing table lookup would cover VPN availability issues, LANs with no gateway (or otherwise defined default route), etc. > I figured the specific-host test pinged the host. I can't imagine it would. Ping would lead to many, many false negatives regarding host availability. A great many sites block ICMP echo requests (I just tried "ping apple.com" for example - and get no response). Since the OS has no way of knowing what particular port/service is of interest, your only good option is to try to connect to the service of interest and handle failure appropriately. (Of course, even if you seemingly can't connect by this approach, it is fundamentally unknowable whether the receiving host actually got your test message: http://en.wikipedia.org/wiki/Two_Generals%27_Problem) - -- Conrad Shultz Synthetiq Solutions www.synthetiqsolutions.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iD8DBQFN5t7faOlrz5+0JdURAiXSAJ92OKchqiDg5NFuQ7Z/GF9aYr18JwCfRCKE WDaiNrv5I/vDSAvQsxmQU40= =wgKX -----END PGP SIGNATURE----- _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
