柳田です。

ruby_1_8 の先頭で、Resolv.getaddress が次のようにエラーになります。
Cygwin と Debian etch 上で確認しています。

% ruby -v -rresolv -e 'p Resolv.getaddress("www.ruby-lang.org")'
ruby 1.8.6 (2008-04-01 patchlevel 5000) [i386-cygwin]
/usr/local/lib/ruby/1.8/resolv.rb:392:in `each_address': undefined
method `address' for #<Resolv::DNS::Resource::IN::CNAME:0x7ff6b204>
(NoMethodError)
        from /usr/local/lib/ruby/1.8/resolv.rb:523:in `extract_resources'
        from /usr/local/lib/ruby/1.8/resolv.rb:1154:in `each_answer'
        from /usr/local/lib/ruby/1.8/resolv.rb:1153:in `each'
        from /usr/local/lib/ruby/1.8/resolv.rb:1153:in `each_answer'
        from /usr/local/lib/ruby/1.8/resolv.rb:522:in `extract_resources'
        from /usr/local/lib/ruby/1.8/resolv.rb:506:in `each_resource'
        from /usr/local/lib/ruby/1.8/resolv.rb:900:in `resolv'
        from /usr/local/lib/ruby/1.8/resolv.rb:898:in `each'
         ... 9 levels...
        from /usr/local/lib/ruby/1.8/resolv.rb:109:in `each_address'
        from /usr/local/lib/ruby/1.8/resolv.rb:87:in `getaddress'
        from /usr/local/lib/ruby/1.8/resolv.rb:38:in `getaddress'
        from -e:1

-- 
Kouhei Yanagita <yanagi at shakenbu.org>