You've got SQL Server connection problems—or you will, at some point. And of course the error message that you get says something unhelpful. As you troubleshoot, keep in mind these seven symptoms and solutions.
7. The SQL Server service isn't
running.
To check the status of the SQL Server service,
open the Administrative Tools menu and
navigate to Services, SQL Server service, and
make sure it's started.
6. The TCP/IP port is blocked by a
firewall.
You need to make sure the firewall is configured to allow SQL Server traffic. By default,
the SQL Server database engine listens for
requests on TCP port 1433, which needs to
be open on any intervening firewalls.
5. SQL Server isn't listening on port
1433.
Some organizations change SQL Server's
default port 1433 for security reasons. To direct the client connections to the correct
port number, configure the TCP port by
using SQL Server Configuration Manager
or by specifying the port on the applications
connection string using the port number
keywords.
4. You attempt to connect to a
named instance and the SQL
Server Browser service isn't running or UDP port 1434 is blocked.
To start the SQL Server Browser service,
which provides information about SQL
Server instances, use SQL Server Configuration Manager. If you're using default ports,
be sure that UDP port 1434 is open on the
firewall or specify the correct port for the
SQL Server instance you're connecting to in
the application's connection string.
3. SQL Server and the client
application aren't configured to
use the same network protocol.
Using SQL Server Configuration Manager,
confirm that both the server and the client
computers have at least one enabled protocol
in common and check for the network
libraries in use. If the server is using TCP/IP
but the network client is using the Shared
Memory Net-Library, they won't connect.
The server and the client must use matching
network libraries.
2. You can't resolve the server
name.
You can test for network name resolution by
using the Ping command with the name of
the SQL Server system (e.g., Ping MyServer).
If the Ping command fails using the server
name, you might have a network name-resolution problem, caused by DNS problems.
1. You can't connect using the IP
address.
If everything else looks right, try to connect
to SQL Server using the server IP address
(e.g., Ping 192.168.100.1). Using the Ping
command with the IP address tests basic
network connectivity with the server. If the
Ping command fails, your problem is with
networking, not SQL Server.
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