title: Why can I connect to a SQL Server 2005 instance using sqlcmd but not SSMS after IP change?
body: <p>We have a couple of SQL Server instances at our main office, and one on our colocated web server.  There are a few replications that handle data exchange between the web server and the main office servers.</p>
  
  <p>We switched ISPs today at our main office.  We did our homework and were ready for the switch (ips in hosts files changed, etc...)  As soon as we switched over to the new connection, all replications completely broke.  I tried to connect to our main office servers using SSMS; no cookie.  We can ping and ftp to our home office servers just fine using server names from our web server.  I saw that ports 1433 and 1434 were blocked by the new ISP, and notified the appropriate people; they should be unblocked now.  Still no dice from SMSS.</p>
  
  <p>I then tried connecting with sqlcmd, which amazingly worked.  SMSS won't connect to the server, but sqlcmd will.  Why is this?  Everything worked like a charm before the ISP switch.</p>
  
  <p><strong><em>Example</em></strong></p>
  
  <pre>
  ping homeserver
      success!
  ftp homeserver
      success!
  sqlcmd -S homeserver\instance -U user -P pass
      success!
  - Trying to connect using SSMS, using the same homeserver\instance and user/pass combo
      Provider: SQL Network Interfaces, error: 26 - Error locating server/instance specified) 
  </pre>