kadukiのにっき。

2010-01-28 びっくり。

rubyのMLみて初めて知った。

これでswapできるのな・・・。

a = 3
b = 2
c = 4

puts "a = #{a}"
puts "b = #{b}"
puts "c = #{c}"

a, b, c  = c, a, b

puts "after swap-----"
puts "a = #{a}"
puts "b = #{b}"
puts "c = #{c}"

2009-12-04 Google DNSと比較

Google DNSと国内のDNSの比較

そんなわけで下に書いたスクリプトを使ってGoogle DNSと国内のDNSのどっちが早いか調べてみたよ。

国内のDNSはぐぐって検索したら出てきたIPアドレスを使ってます。

問い合わせ元は国内の某大学デス。テストPCはCentOS5.3。DNS キャッシュの影響はないはず・・・。

問い合わせたホスト名

国内
- [www.yahoo.co.jp]
- [www.goo.jp]
- [www.excite.co.jp]
- [www.asahi.com]
- [www.livedoor.com]
- [www.nicovideo.jp]
- [mixi.jp]
- [www.youtube.com]
- [www.amazon.co.jp]
- [www.msn.co.jp]
国外?
- [www.yahoo.com]
- [wikipedia.org]
- [baidu.com]
- [myspace.com]
- [twitter.com]

スクリプト


national_host = ["www.yahoo.co.jp", "www.goo.jp", "www.excite.co.jp", "www.asahi.com", "www.livedoor.com","www.nicovideo.jp", "mixi.jp", "www.youtube.com", "www.amazon.co.jp","www.msn.co.jp" ]
n_first = national_host

foreign_host = ["www.yahoo.com", "wikipedia.org", "baidu.com", "myspace.com","twitter.com"]
f_first = foreign_host

dns = {"google" => "8.8.8.8"}

class Dns_statistics
  
  def initialize
    @time_array = Array.new
  end

  def time_push(dns_rtt)
    @time_array.push(dns_rtt)
  end

  def average
    sum = 0
    @time_array.each{|time|
      sum += time
    }
    return sum / @time_array.length
  end
    
end

def nslookup_test(dns_host, host)
  
  before = Time.now.to_f * 1000
  return_message = `nslookup #{host} #{dns_host}`
  after = Time.now.to_f * 1000

  if (return_message =~ /REFUSED/)
    puts "error! #{dns_host} refused"
  end
    
  if(after < before)
    puts "error! #{after} #{before}"
  end
  return after - before
end

def host_search(hosts, dnsip, dnsname)

  sum = 0
  hosts.each{|host|
    statistics = Dns_statistics.new
    for i in 1..10
      result = nslookup_test(dnsip, host)
      statistics.time_push(result)
    end
    avg = statistics.average
    sum += avg
    printf "  [%s] average = %.2f\n", host, avg
  }
  dns_average = sum / hosts.length
  printf "[%s] avg = %.2f\n", dnsname, dns_average
end

dns.each{|dnsname, dnsip|
  
  puts "--------------------------------"
  puts "#{dnsname}"
  puts "--------------------------------"

  puts "[national]"
  host_search(national_host, dnsip, dnsname)
  puts "[foreign]"
  host_search(foreign_host, dnsip, dnsname)
 
}