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</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link=blue vlink=purple style='text-justify-trim:punctuation'><div class=WordSection1><p class=MsoNormal><span lang=EN-US>Hi folks, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>I¡¯m writing to ask if any resolver operator is doing or be asked to do aggressive pre-fetch for popular names in the case of urgent changes of owners¡¯ names. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>The problem space is some concerns and complains on DNS TTL which usually makes mis-configured or hacked RR stick around for long time than name owner expected. </span><span lang=EN-US style='color:#222222;background:white'>TTL 1 ~2 day even hours will make huge damage (if the user based are large) and the name owner can do nothing about it but wait unless the DNS resolver can be notified to fix it.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'>I do know the context of </span><span lang=EN-US style='color:#222222'>draft<span style='background:white'>-</span>wkumari<span style='background:white'>-</span>dnsop<span style='background:white'>-</span>hammer (thanks to Mukund¡¯s reminder<span style='background:white'>,) but it is not aggressive enough. It pre-fetch only when it is close to the end of TTL. The intuitive approach to address the problem in my mind is to prefecth the popular names every 30 seconds or less on popular resolvers. The performance optimization can be done using a separate special server other than the busy resolver.<o:p></o:p></span></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'>I wonder If it was discussed before or any obstacle exist which make this problem unresolved. Or any performance and risk tradeoff there. Thanks in advance.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'>Best regards, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#222222;background:white'>Davey</span><span lang=EN-US><o:p></o:p></span></p></div></body></html>