Can't connect to instance name - need explaination rather than ans

I'm really looking for an explaination rather than an answer...
I can't connect to sql instances on a specific server using the normal
structure of <servername>\<instancename> but I can connect to
<servername>,<portnumber>.
I've tried many different connection tests (OSQL, udl file, Ent Mngr) and
instance name doesn't work unless I configure the Client Net Utility to use
a
specific port number for this instance.
What I don't understand is whats failing? Is this the server failing to
resolve inbound traffic for a instance name to the port number used? If so
what actually performs this name-to-port-number resolution?
My dev team are particularly technical & when I tell them they have to
connect using <servername>,<portnumber> they'll want to know why I can't fix
it on the server...
Thnx
Steve
Steve Morgan
MCDBA
Snr Production DBAWell...it's a bit difficult to give an explanation for a
problem when the problem hasn't been identified. But here is
an explanation of connecting to named instances: If you try
to connect to YourServer\YourNamedInstance and that's what
you specify for the connection, it hits UDP 1434 to use the
SQL Server Resolution Service to find what port number
YourServer\YourNamedInstance is listening on. You can
bypass that by specifying the port yourself and then there
is no need to go through UDP 1434.
At a high level, that's one of the primary connection
difference with name instances and when you specify a port
number and when you don't.
-Sue
On Tue, 30 Nov 2004 08:49:03 -0800, Steve Morgan
<SteveMorgan@.discussions.microsoft.com> wrote:

>I'm really looking for an explaination rather than an answer...
>I can't connect to sql instances on a specific server using the normal
>structure of <servername>\<instancename> but I can connect to
><servername>,<portnumber>.
>I've tried many different connection tests (OSQL, udl file, Ent Mngr) and
>instance name doesn't work unless I configure the Client Net Utility to use
a
>specific port number for this instance.
>What I don't understand is whats failing? Is this the server failing to
>resolve inbound traffic for a instance name to the port number used? If so
>what actually performs this name-to-port-number resolution?
>My dev team are particularly technical & when I tell them they have to
>connect using <servername>,<portnumber> they'll want to know why I can't fi
x
>it on the server...
>Thnx
>Steve