ORA-12545: Connect failed because target host or object does not exist

Hi experts,

I have been trying to investigate issue related ORA-12545. The strange thing is whenever I tried to connect oracle 10G R2 RAC database(devsrv) through TOAD then it throws ORA-12545 error. After attempting 3 or 4 times, it will connect to the database. we have several databases are there on these hosts meaning all host IPs in the TNSNAMES.ORA file are same and only service name will be different. When I try to connect database (qasrv) then it never allows me to login to this database.

here is the TNSNAME I'm using to connect database.

AEQASRV=
  (DESCRIPTION=
    (LOAD_BALANCE=yes)
    (ADDRESS_LIST=
      (ADDRESS=
        (PROTOCOL=TCP)
        (HOST=10.100.100.120)
        (PORT=1521)
      )
      (ADDRESS=
        (PROTOCOL=TCP)
        (HOST=10.100.100.121)
        (PORT=1521)
      )
      (ADDRESS=
        (PROTOCOL=TCP)
        (HOST=10.100.100.123)
        (PORT=1521)
      )
    )
    (CONNECT_DATA=
      (FAILOVER_MODE=
        (TYPE=select)
        (METHOD=basic)
        (RETRIES=180)
        (DELAY=5)
      )
      (SERVER=dedicated)
      (SERVICE_NAME=aeqasrv)
    )
  )

One more thing, we have a developer who is accesing same QA database from his machine with out any issues. Is there any network settings do I need to adjust or tweek in order to connect to database? Any help would be appreciated.
 
KuldeepReddyAsked:
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riazpkCommented:
I just faced this issue recently. We were getting the same error while trying to connect our RAC Database. The solution is to add vip host name in the DNS (or in the hosts file but i prefer adding it in DNS because you can have more than one client trying to connect to this db and adding entries in DNS will avoid adding entries in hosts file of each client).
Once we did this, everything was perfectly ok.
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j_coreilCommented:
Check the sqlnet files on both machines and compare them. Another thing to check, I've encountered this in 11g not 10g, is that the problem PC's dns settings are correct. In 11g, there is a known bug where if you cannot get to the primary DNS entry, it will have to timeout first before it attempts the secondary DNS entry. This process can take upwards to 2 minutes per request to the DNS server. So each session you try to open could possibly take forever.
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sammySeltzerCommented:
hi,

can you try pinging <SERVER_NAME>

If you do not get a response from the server this is your problem. try the same ping with the IP address of the server.

assuming you get a response when you specify the IP address but not the server name then you have a simple problem with DNS names resolution,

Also, check to see if you have virus scanner on that server. It is often guilty of interferring.
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j_coreilCommented:
Windows Firewall can sometimes be causing this problem. I would only disable it temporarily for testing.
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sumit2906Commented:
This could be issue with the client, sometimes having multiple homes could cause issues like this. Also, you can use tnsping <alias> command to know whether your tns settings are fine.
0
 
tangchunfengCommented:
1. use hostname not IP address in your oracle tnsnames.ora
2. set hostname/ip pairs in c:\windows\system32\drivers\etc\hosts
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