反向DNS每次都会返回一个不同的主机

所以，随机我碰巧平abc.com，发现这个迷人的：

$ ping abc.com PING abc.com (199.181.132.250) 56(84) bytes of data. 64 bytes from m.abc.com (199.181.132.250): icmp_req=1 ttl=237 time=90.3 ms 64 bytes from tdl.disneyuniversity.com (199.181.132.250): icmp_req=2 ttl=237 time=89.8 ms 64 bytes from preschooltime.go.com (199.181.132.250): icmp_req=3 ttl=237 time=95.1 ms 64 bytes from futbolpicante.espnfc.com (199.181.132.250): icmp_req=4 ttl=237 time=98.6 ms 64 bytes from www.worldofcars.go.com (199.181.132.250): icmp_req=5 ttl=237 time=86.9 ms 64 bytes from www.verizon.bravesweepstakes.com (199.181.132.250): icmp_req=6 ttl=237 time=87.9 ms 64 bytes from www.directv.bravesweepstakes.com (199.181.132.250): icmp_req=7 ttl=237 time=87.9 ms 64 bytes from manup.abc.com (199.181.132.250): icmp_req=8 ttl=237 time=88.8 ms 64 bytes from m.onemoredisneyday.com (199.181.132.250): icmp_req=9 ttl=237 time=87.5 ms 64 bytes from finance.abc30.com (199.181.132.250): icmp_req=10 ttl=237 time=87.9 ms 64 bytes from finance.abc13.com (199.181.132.250): icmp_req=11 ttl=237 time=88.0 ms ...

在某种程度上，它类似于在正向DNS中使用的负载平衡，除非我不明白这是如何有用的。

这是否有任何实际的原因，或只是这些网站都在同一个IP地址背后的后果？

nslookup 199.181.132.250显示了一堆非权威的答案为不同的域名。但是我的ping不像你的那样dynamic变化。

它真的看起来有人只是有趣，或服务器configuration错误或类似的东西。实际上有很多反向logging。

顺便说一句。我怀疑这个IP可能被用来分发垃圾邮件和这些主机名在那里混淆filter。（但这是一个疯狂的猜测）

看到：

 $ dig 250.132.181.199.in-addr.arpa -t PTR ;; Truncated, retrying in TCP mode. ; <<>> DiG 9.7.3 <<>> 250.132.181.199.in-addr.arpa -t PTR ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33536 ;; flags: qr rd ra; QUERY: 1, ANSWER: 195, AUTHORITY: 4, ADDITIONAL: 2 ;; QUESTION SECTION: ;250.132.181.199.in-addr.arpa. IN PTR ;; ANSWER SECTION: 250.132.181.199.in-addr.arpa. 180 IN PTR m.nightofjoy.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.disneyworld.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.mustdodisney.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.disneytheforce.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.onemoredisneyday.com. 250.132.181.199.in-addr.arpa. 180 IN PTR s.espnradio.com. 250.132.181.199.in-addr.arpa. 180 IN PTR fb.steelgetsreal.com. 250.132.181.199.in-addr.arpa. 180 IN PTR my.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR qa.watchdisneyxd.com. 250.132.181.199.in-addr.arpa. 180 IN PTR qa.watchabcfamily.com. 250.132.181.199.in-addr.arpa. 180 IN PTR qa.watchdisneyjunior.com. 250.132.181.199.in-addr.arpa. 180 IN PTR qa.watchdisneychannel.com. 250.132.181.199.in-addr.arpa. 180 IN PTR uk.disneycareers.com. 250.132.181.199.in-addr.arpa. 180 IN PTR abc.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR cdn.musiclounge.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR fdj.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR fdj.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR gma.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hdf.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hub.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR itm.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR lnb.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR sam.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR tdl.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR ugc.lionking.com. 250.132.181.199.in-addr.arpa. 180 IN PTR ugc.marypoppins.com. 250.132.181.199.in-addr.arpa. 180 IN PTR ugv.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR vpd.disneycruise.com. 250.132.181.199.in-addr.arpa. 180 IN PTR w88.m.fwfest.waltdisneyworld.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.att.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.cox.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.ttdl.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.enter.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.charter.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.directv.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.verizon.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.mediacom.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.adventure.bravesweepstakes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyhome.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.worldofcars.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneycasting.net. 250.132.181.199.in-addr.arpa. 180 IN PTR www.donovandecker.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyroommate.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneycampusrep.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneycollateral.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyinternsinfo.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.missiontimekeeper.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneycastingscout.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyimaginations.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyprogramsblog.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.wdwcollegeprogramecard.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.wdwcollegeprogramecard2.com. 250.132.181.199.in-addr.arpa. 180 IN PTR www.disneyinternationalepresentation.com. 250.132.181.199.in-addr.arpa. 180 IN PTR 1ext.doit.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR 25th.disneystore.com. 250.132.181.199.in-addr.arpa. 180 IN PTR beta.xgames.com. 250.132.181.199.in-addr.arpa. 180 IN PTR blog.disneyxd.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR bmoc.abc7chicago.com. 250.132.181.199.in-addr.arpa. 180 IN PTR doit.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR live.dadt.com. 250.132.181.199.in-addr.arpa. 180 IN PTR live.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR play.toontown.com. 250.132.181.199.in-addr.arpa. 180 IN PTR prod.waltdisneystudios.com. 250.132.181.199.in-addr.arpa. 180 IN PTR ugv2.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR blogs.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR cards.babyzone.com. 250.132.181.199.in-addr.arpa. 180 IN PTR email.doit.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR email.disneymovieclub.com. 250.132.181.199.in-addr.arpa. 180 IN PTR espn3.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR games.soapnet.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR manup.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR panam.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR castle.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR comedy.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR espnrf.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hdfmas.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR health.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR mobile.abcfamily.com. 250.132.181.199.in-addr.arpa. 180 IN PTR oscars.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR photos.kaboose.com. 250.132.181.199.in-addr.arpa. 180 IN PTR photos.babyzone.com. 250.132.181.199.in-addr.arpa. 180 IN PTR search.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR search.video.movies.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR temail.disneymovieclub.com. 250.132.181.199.in-addr.arpa. 180 IN PTR tienda.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR topics.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR velti2.disneylandsummer.com. 250.132.181.199.in-addr.arpa. 180 IN PTR workit.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR 999test.abcnews.com. 250.132.181.199.in-addr.arpa. 180 IN PTR account.toontown.com. 250.132.181.199.in-addr.arpa. 180 IN PTR casting.disneyparks.jobs. 250.132.181.199.in-addr.arpa. 180 IN PTR catalog.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR clarity.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR culture.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.6abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc7.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc11.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc13.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc30.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.7online.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc7news.com. 250.132.181.199.in-addr.arpa. 180 IN PTR finance.abc7chicago.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hotseat.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR missing.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR playdom.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR preview.mydisneyphotopass.com. 250.132.181.199.in-addr.arpa. 180 IN PTR revenge.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR scandal.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR scrumtv.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR search2.spanish.disneylandsummer.com. 250.132.181.199.in-addr.arpa. 180 IN PTR theview.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR topics2.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR uplayit.abc7chicago.com. 250.132.181.199.in-addr.arpa. 180 IN PTR developu.disneyuniversity.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyhd.tv. 250.132.181.199.in-addr.arpa. 180 IN PTR polo2011.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR theriver.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR whereami.doit.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR abccomedy.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR helpoffer.com. 250.132.181.199.in-addr.arpa. 180 IN PTR rugby2011.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR shelterme.6abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR stagepass.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR tenis2011.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR themiddle.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR trongames.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR cougartown.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR devicedata.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneytime.disneyparks.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyvisa.com. 250.132.181.199.in-addr.arpa. 180 IN PTR experience.disneydestinations.com. 250.132.181.199.in-addr.arpa. 180 IN PTR happyrides.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR portfolios.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR storefront.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR bodyofproof.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR copavirtual.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR desafioeuro.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyparks.jobs. 250.132.181.199.in-addr.arpa. 180 IN PTR familytools.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR glass-house.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hipcricket2.spanish.disneylandsummer.com. 250.132.181.199.in-addr.arpa. 180 IN PTR klubpenguin.de. 250.132.181.199.in-addr.arpa. 180 IN PTR klubpinguin.de. 250.132.181.199.in-addr.arpa. 180 IN PTR musiclounge.abc.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR preolimpico.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR radiodisney.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR suburgatory.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR weatherblog.abc13.com. 250.132.181.199.in-addr.arpa. 180 IN PTR abcdotcomedy.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR euroquiniela.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR happyendings.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR modernfamily.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR sendtofriend.abcnews.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR desafiofutmex.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR dimgpressroom.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneypackage.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneystudios.com. 250.132.181.199.in-addr.arpa. 180 IN PTR futbolpicante.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR golesdeeuropa.espnfc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR onceuponatime.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR preschooltime.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR rincontecnico.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR yourcommunity.6abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR desafiopremier.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR phineasandferb.disneymags.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyparksblog.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyvisaperks.com. 250.132.181.199.in-addr.arpa. 180 IN PTR elmejorejemplar.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR lastmanstanding.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR monstroussummer.disneyparks.com. 250.132.181.199.in-addr.arpa. 180 IN PTR the-glass-house.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyconnection.com. 250.132.181.199.in-addr.arpa. 180 IN PTR avalanchesoftware.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR celebritywifeswap.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyhumanrights.org. 250.132.181.199.in-addr.arpa. 180 IN PTR disneysecondscreen.com. 250.132.181.199.in-addr.arpa. 180 IN PTR watchdisneychannel.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hablemosdefutbolmas.espndeportes.com. 250.132.181.199.in-addr.arpa. 180 IN PTR mickeystrickortreat.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneylearningstudio.com. 250.132.181.199.in-addr.arpa. 180 IN PTR shanghaidisneyresort.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneystarbuckssurvey.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyworldsvacations.com. 250.132.181.199.in-addr.arpa. 180 IN PTR wheelchairrentaldisney.com. 250.132.181.199.in-addr.arpa. 180 IN PTR hyperionbooksforchildren.com. 250.132.181.199.in-addr.arpa. 180 IN PTR disneyparksstarbuckssurvey.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.abc.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.test.doit.go.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.fwfest.waltdisneyworld.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.abcfamily.com. 250.132.181.199.in-addr.arpa. 180 IN PTR m.bostonmed.abcnews.go.com. ;; AUTHORITY SECTION: 132.181.199.in-addr.arpa. 180 IN NS sens01.dig.com. 132.181.199.in-addr.arpa. 180 IN NS orns01.dig.com. 132.181.199.in-addr.arpa. 180 IN NS sens02.dig.com. 132.181.199.in-addr.arpa. 180 IN NS orns02.dig.com. ;; ADDITIONAL SECTION: orns01.dig.com. 257 IN A 68.71.223.14 sens02.dig.com. 242 IN A 199.181.135.199 ;; Query time: 7 msec ;; SERVER: 192.168.0.1#53(192.168.0.1) ;; WHEN: Fri Apr 19 23:24:14 2013 ;; MSG SIZE rcvd: 5471

这用于“正向确认的反向DNS”。从维基百科

FCrDNSvalidation可以创build一种弱的身份validationforms，即域名所有者和已经被赋予IP地址的networking所有者之间存在有效的关系。虽然弱，但这种身份validation足够强大，可以用于白名单的目的，因为垃圾邮件制造者和钓鱼者通常不能通过这种validation时，他们使用僵尸电脑的邮件欺骗。也就是说，反向DNS可能会validation，但它通常会是声明的域名之外的其他域的一部分。

但是，我知道没有应用程序，实际上看超过1 PTR RR。迪斯尼可能有一些服务看起来不止一个PTR RR。