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  • 1.  AIX IPv6 - How to make OS prefer IPv6 over IPv4

    Posted Fri July 20, 2012 02:22 PM

    Originally posted by: jordanbean


    Salutations,

    I am working with AIX 5.x, 6.x and 7.x with IPv6 configured concurrently with IPv4. As far as I understand, IPv6 should be the preferred transport. This is the behavior on Solaris, Linux, and Apple OS X, but not on AIX. Should AIX prefer IPv6? Is this configurable? What am I missing?

    In /etc/hosts I have the node's IPv6 address defined before the its IPv4 address.
    In DNS I have both AAAA and A records in the zone for everything, as well as ip6.int and ip6.arpa zones for reverse resolution.

    I've tried using the name server's IPv6 address in /etc/resolv.conf, as well as its IPv4 address.
    I've tried using hosts=local6,local4,bind6,bind4 in /etc/netsvc.conf.

    No matter how the OS are configured, these AIX servers always use IPv4 instead of IPv6. The only way I can coerce the use of IPv6 is to eliminate IPv4, at least from any name resolution.

    I appreciate any advise anyone can provide.

    Regards,


  • 2.  Re: AIX IPv6 - How to make OS prefer IPv6 over IPv4

    Posted Mon July 23, 2012 11:38 PM

    Originally posted by: SystemAdmin


    Hi Jordan,

    Strange, but I would have said that AIX uses IPv6 first, then IPv4. The reason I say this is several years ago one of our DNS servers went down, and caused us problems. Our DNS servers use IPv4 and at that stage the /etc/netsvc.conf did not contain a mention of bind4. The effect was that the AIX systems tried the first DNS server, concluded that they wanted IPv6 not 4, then waited 90 seconds for the second DNS server to respond, before finally accepting the IPv4 address. We found that using the IPv4 address gave an immediate connection, as did adding bind4 to netsvc.conf.

    I would suggest checking out your DNS servers. What do you see returned when you use nslookup?

    Regards,
    George


  • 3.  RE: AIX IPv6 - How to make OS prefer IPv6 over IPv4

    Posted Tue August 23, 2022 04:30 AM
    Hello,

    It might seem odd to continue the decade-old thread.
    I am trying to connect with some hosts from the AIX server, but the host's IP is resolved from the name server. When I perform nslookup to the host it gives me the IPv4 address of the host and when I perform telnet to the same host it tries to connect using IPv6 address. It takes longer to verify that it cannot establish the connection and retries using IPv4 and only after this connection is established.
    The problem is it takes so long trying to connect to IPv6 address and wastes much time.
    I want to configure OS, that prefers IPv4 connection so it does not goest to connect for IPv6 address.
    Defined hosts=local4,bind4 in /etc/netsvc, which did not worked.
    The aim is to redirect the connection to the IPv4 address, adding IP to /etc/hosts is not an option as the IP or the port changes frequently.

    Thanks, and Regards

    ------------------------------
    Anup Regmi
    ------------------------------

    Original Message


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