Using Directory.Exists for UNC path is sloowwwwww

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

css - 22 Dec 2005 15:59 GMT

When I call Directory.Exists for a UNC path like below...

if (Directory.Exists(@\\SomeServer\C) == false)
{
....
}

and that server does not exist on the connected network, it takes around a
minute to return from the call which properly returns false.

Is there a faster way to determine if a directory or server exists on the
network?

Reply to this Message

Vadym Stetsyak - 22 Dec 2005 16:26 GMT

When you try to access remote server, network redirector tries to get the
address of the server. It issues DNS query. This process takes a while...

AFAIK there can be several solutions:
- if you know the IP address of the server, try to connect to it on 135-139
( for UNC )
- if you know the IP substitue it into the UNC path.
- if you do not know the IP try to resolve it manually using Dns.Resolve (
.NET 1.0 - 1.1 )
or GetHostEntry ( .NET 2.0 )

Signature

Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

> When I call Directory.Exists for a UNC path like below...
>
[quoted text clipped - 8 lines]
> Is there a faster way to determine if a directory or server exists on the
> network?

Reply to this Message

css - 22 Dec 2005 19:58 GMT

Vadym,

I don't know the IP. If I use or GetHostEntry() it resolves to a name
without throwing an exception even if the server doesn't exist! If I put

a legit name like:

GetHostEntry("\\MyLocalMachineName")

it returns "MyLocalMachineName.hilton.com" but the IP is 0.0.0.1. (Which is
incorrect I am using a wirless connection at the Hilton hotel and the DHCP
address is 10.252.1.100).

If I use an illegit name, like
GetHostEntry("\\VADYM")

it returns "VADYM.hilton.com" and the IP is also 0.0.0.1.

Am I missing something?

Reply to this Message

Vadym Stetsyak - 23 Dec 2005 11:30 GMT

GetHostEntry returns the list of ips, did you check the whole list?
smth like

IPHostEntry host;
host = Dns.GetHostEntry(hostname);

Console.WriteLine("GetHostEntry({0}) returns:", hostname);

foreach (IPAddress ip in host.AddressList)
{
Console.WriteLine(" {0}", ip);
}

Signature

Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

> Vadym,
>
[quoted text clipped - 16 lines]
>
> Am I missing something?

Reply to this Message

Willy Denoyette [MVP] - 24 Dec 2005 18:48 GMT

Why are you trying this for a path (server) that doesn't exists in the first
place? Why not ping the server before trying to connect to a remote share
exposed by the server?

Willy.

> When I call Directory.Exists for a UNC path like below...
>
[quoted text clipped - 8 lines]
> Is there a faster way to determine if a directory or server exists on the
> network?

Reply to this Message

Using Directory.Exists for UNC path is sloowwwwww

Free Magazines