How to Troubleshoot Distributed Transactions ? (ORA-2019, ORA-2058, ORA-2068, ORA-2050, FAILED DISTRIBUTED TRANSACTIONS)

How to Troubleshoot Distributed Transactions ? 

Database "A" has init.ora parameter 
db_domain incorrectly specified as ".WORLD", that causes the init.ora parameter "service_names" to be "A..WORLD". 

A select from GLOBAL_NAMES shows "A.WORLD". Database "B" has init.ora parameters of "db_domain=WORLD" and SERVICE_NAMES=B.WORLD". 

Select from GLOBAL_NAME shows "B.WORLD". The table synonyms referring to the remote tables work for both databases to data manipulation. But, the synonyms on database "A" cannot be used to describe the tables on "B" (ORA-02019). 

Can I safely change the "A" init.ora parameter from "db_domain=.WORLD" to "db_domain=WORLD"? I know from my test databases that that parameter inhibits the describe. 

Set GLOBAL_NAMES=FALSE in the init.ora and restart the database.

The syntax is as follows: 
Create public database link  
Connect to uid identified by pw 
Using 'alias'; 

Ensure that global_names = true in the destination server's init.ora file. If the global name = true parameter is set in the init.ora, check the value of the db_name and db_domain parameters in that same init.ora file. Log into the destination server via sqlplus and do a SELECT * FROM GLOBAL_NAME. This value should match the db_name specified in the init.ora file. If the global name = true parameter exists in the init.ora file, then the name of the dblink must be either that databases sid or global dbname.