In the case of Host Naming, service names are stored using an IP-Address translation mechanism, ie. a host name alias. Host names are mapped to a server global database name using a names resolution service such as DNS (Domain Name System), NIS (Network Information Service) or even a centrally maintained set of host files such as /etc/hosts. Host Naming can be used without a tnsnames.ora file. Thus only the most simplistic of Oracle network access can be used.Host naming can be used in simplistic environments where no advanced features such as load balancing, failover, connection pooling, etc. are required. Host naming removes the neccessity for lookups into the tnsnames.ora file. Also host naming is only available for TCP/IP connections. The global database name, a concatenation of the database name and the domain name, is used as the host name of an alias for an existing network name resolution service such as DNS. Files shown below constitute example host naming resolution and DNS configuration files for a Solaris box.
# cat /etc/hosts # # Internet host table # 127.0.0.1 localhost 2220.127.116.11 dev dev.xyz.com loghost 218.104.22.168 test test.xyz.com 222.214.171.124 prod prod.xyz.com # cat /etc/resolv.conf search localdomain domain xyz.com nameserver 2126.96.36.199 nameserver 2188.8.131.52 nameserver 2184.108.40.206 nameserver 127.0.0.1