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Does spoofing, on DR server, need to be removed when failing over to DR?

long TRUONG (3654119146) | asked Apr 03 '16, 2:19 p.m.
edited Apr 04 '16, 3:28 a.m. by Mehul Patel (9695)
 We are revisiting our DR strategy for RTC/RRC 5.0.2 on Windows/Tomcat, and found spoofing 
(with line "<DRserverIPaddress>  <DNSalias4publicURI4CLMserverOnPRD"
in the C:\Windows\System32\drivers\etc\hosts file) was used to verify that DR is in working order.

We did not find any infos in the failover to DR procedures on the removing of spoofing: We believe that does not matter, the spoofing should not have any harmful effect on the running of CLM in DR. 

Wonder if we overlook anything, so thinking.

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Donald Nong (14.5k414) | answered Apr 06 '16, 3:29 a.m.
I don't think spoofing has ever been suggested in DR planning, and that's probably why you cannot find any information about it. IIRC the only situation that spoofing is mentioned in official documents is when setting up a staging environment using production data for evaluating upgrade process.

I don't know how you will switch over to the DR server in case the PRD is down. If you simply change the DNS entry to point the FQDN to the DR server address, it will have the same effect as the entry in the hosts file. In this case, the particular line in the hosts file is just fine. But if you re-assign the PRD server IP address to the DR server (which is rare), then you must remove the line in the hosts file.
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long TRUONG commented Apr 06 '16, 3:15 p.m.

 Thx Don,

If spoofing is not used, how could we verify if DR works on PRD DB's, with PRD live? The only way to verify, other than spoofing, is the real DR test, with PRD down?

Donald Nong commented Apr 12 '16, 3:20 a.m.

I don't think you can make two applications connect to the same database at the same time. It is way too easy to cause data corruption, even when you think you're not updating any records. The application should refuse to do so anyway. That's why we use the term "cold standby" in the DR planning.

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