Motivation:
1. The use of InternetProtocolFamily is not consistent:
the DnsNameResolverContext and DnsNameResolver contains switches
instead of appropriate methods usage.
2. The InternetProtocolFamily class contains redundant switches in the
constructor.
Modifications:
1. Replacing switches to the use of an appropriate methods.
2. Simplifying the InternetProtocolFamily constructor.
Result:
Code is cleaner and simpler.
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