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if I'm accessing a local file via UNC path, for example //hostname/abc.txt, Will the traffic still go through the switch or it's clever enough to figure out this is a local machine, i.e. will there be a significant speed impact if I'm accessing a file via a UNC path rather than its local path (d:\abc.txt, for example)


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Disconnect from the network and check. Or monitor the traffic on your switch. – HopelessN00b Jul 26 '12 at 10:35
Thanks, but in a corporate environment I don't really have the ability to disconnect from the network and monitor the traffic on the switch, maybe I can test it later at home. – Godsent Jul 26 '12 at 10:49
up vote 4 down vote accepted

File sharing is based on ordinary TCP/IP, so the rules are no different than those that apply to other network applications. Hostnames from UNC paths will always be resolved first using DNS or NetBIOS and then the traffic will sent out based on a routing table. Since it will resolve to a local address, the traffic will never go out, unless you have some very strange rules on a machine (I am not sure if it is even possible to create such a setup).

As for the speed, I am not so sure if it is smart enough not to use TCP/IP (even if packets never leave the machine) when connecting to a local address. If it does use TCP/IP, local file access will be faster as it does not have the network socket overhead. You can test this with a packet analyser, like Wireshark (see this link to see how to set up a capture on a local interface).

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Thanks Tibor!!! – Godsent Jul 26 '12 at 11:32

Depends on the OS but 99% sure it won't no.

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Thanks! The OS is windows server 2008 the difference between using a UNC path and a local path should be minimum? – Godsent Jul 26 '12 at 10:41
It doesn't depend on the OS. If it sent the traffic out -- what would send it back? – David Schwartz Jul 26 '12 at 11:50
I was worried about it may take a round trip if all traffics are forced to go through the switch in LAN.. Apparently, I'm just plain stupid.. ;) – Godsent Jul 26 '12 at 11:54

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