| DnsResolver | Helper class for DNS operations. |
| InitialContextFactory | This is used in JndiDnsResolver to get an InitialDirContext for DNS queries. |
| JndiDnsResolver | Implementation of DnsResolver which uses JNDI for the DNS queries. |
| DnsEntryNotFoundException | This will be thrown if no entry matches the specified DNS query. |
| DnsLookupException | This will be thrown for unknown DNS errors. |