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Posted to issues@trafficserver.apache.org by pubyun <gi...@git.apache.org> on 2017/03/10 06:56:50 UTC

[GitHub] trafficserver issue #1562: dns Negative cache

GitHub user pubyun opened an issue:

    https://github.com/apache/trafficserver/issues/1562

    dns Negative cache

    tcpdump shows that ATS will query DNS server for a non-exist host name every time.
    
    there is no dns Negative cache in ATS.
    
    i test ATS 6.2.1.

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[GitHub] trafficserver issue #1562: dns Negative cache

Posted by pubyun <gi...@git.apache.org>.
Github user pubyun commented on the issue:

    https://github.com/apache/trafficserver/issues/1562
  
    maybe another issue:
    
    ATS will try ipv6 dns resolve for non-exist host name every time also i config flowing config:
    
    CONFIG proxy.config.hostdb.ip_resolve STRING ipv4;none
    
    
    sudo tcpdump -i em1 -n port 53                                                                                                                                                                                                                                                                                                                                        <<<
    tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
    listening on em1, link-type EN10MB (Ethernet), capture size 65535 bytes
    
    14:53:09.523847 IP 118.184.176.21.26037 > 118.184.176.35.domain: 42650+ A? www.pubyun.com.dns139.com. (43)
    14:53:09.524741 IP 118.184.176.35.domain > 118.184.176.21.26037: 42650 NXDomain* 0/1/0 (96)
    14:53:09.545515 IP 118.184.176.21.49774 > 118.184.176.38.domain: 27685+ AAAA? www.pubyun.com.dns139.com. (43)
    14:53:09.546240 IP 118.184.176.38.domain > 118.184.176.21.49774: 27685 NXDomain* 0/1/0 (96)
    14:53:13.125052 IP 118.184.176.21.57917 > 118.184.176.35.domain: 52856+ A? www.pubyun.com.dns139.com. (43)
    14:53:13.125884 IP 118.184.176.35.domain > 118.184.176.21.57917: 52856 NXDomain* 0/1/0 (96)
    14:53:13.146626 IP 118.184.176.21.51052 > 118.184.176.38.domain: 28095+ AAAA? www.pubyun.com.dns139.com. (43)
    14:53:13.147184 IP 118.184.176.38.domain > 118.184.176.21.51052: 28095 NXDomain* 0/1/0 (96)



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