For sql service domain accounts that are NOT domain admins you can configure the service account(s) to create its own SPN on startup so you dont have to worry about the correct syntax for creating the SPN yourself (and also whether or not to create multiple SPNs for clustered instances). If you have 50, 100, 200 sql servers do you really want to be manually configuring/administrating SPNs ?

For each sql service account (which can be running 1 + N sql services) ask the domain administrator to ensure delegation is selected in the domain user account settings. Also you will need to request (or do this yourself CAREFULLY if you have privileges) that your domain admin make the following changes in AD :

Using ADSIEDIT for the sql service account (s) grant permissions to SELF for the following properties :

Read servicePrincipalName

Write servicePrincipalName

This way the SQL server instance will create its own correctly formatted SPN at startup, sql restart is required using this method. Also sql server will not perform any maintenance on this or other SPNs so if you have a large server base you should consider listing the current SPNs to determine if any are redundant or no longer required.