IP to Domain Name Resolving in Oracle

< 해당 문제로 인한 조치사항에 대하여 간략 정리 - 2012.08.22 >

In a nutshell, when creating a connection from a client to server, the client has to use an identifier to specify which server to connect to. This identifier can be an IP address, or hostname. If the latter, the IP address of the hostname needs to be identified. This can be resolved by the protocol stack in two basic ways - using the local hosts file or requesting via the network (DNS/WINS/etc) that the IP address for the hostname be supplied.

So why would Oracle do a resolve? Only when itself uses a hostname and not IP address.

What can a hostname resolve to? A single IP address. If you have 2 or more IP addresses for a hostname, how must the client go about selecting one? They could be different subnets, require different routes, etc. Thus the association between hostname and IP is 1:1 - despite that a single server can have multiple IP addresses.

# DNS 서버 설명 : http://technet.microsoft.com/ko-kr/library/cc753635(v=ws.10).aspx