I previously described how to install 11g Database. I found that it took a long time when connecting to the database from outside the VM, using sqldeveloper, sqlplus, Pl/Sql Developer.

I use a host-only and a bridged adapter in the VM. It took me a while but I found that it has something to do with a DNS-lookup that the database does during the connection process. In my /etc/resolv.conf a reference to the host for the name server is registered. But on my host I don't have a DNS server. It should get it from the physical/bridged network or not at all.

I resolved it by uncommenting the lines in the /etc/resolv.conf (place a semi-colon before each line). Also you change your networksettings in the network-devices. in Oracle Enterprise Linux. On one of the tabs you'll find an entry to the prefered dns-server. And a domain. You should clear those lines.