Why are IPV6 DNS lookups done even when IPV6 is disabled in Red Hat Enterprise Linux?

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The following information has been provided by Red Hat, but is outside the scope of the posted Service Level Agreements and support procedures. The information is provided as-is and any configuration settings or installed applications made from the information in this article could make the Operating System unsupported by Red Hat Global Support Services. The intent of this article is to provide information to accomplish the system's needs. Use of the information in this article at the user's own risk.

  • Applications like ssh and telnet use the getaddrinfo() function with AF_UNSPEC and this function invokes both AAAA (ipv6) and A (ipv4) lookups one after the other. This can delay the connection time when DNS servers block or don't handle IPV6 correctly.


  • Red Hat Enterprise Linux 4
  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • glibc

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