Question on IP address used by anycast DNS cache server
Edward B. Dreger
eddy+public+spam at noc.everquick.net
Mon Oct 11 13:31:47 UTC 2004
JS> Date: Mon, 11 Oct 2004 17:23:19 +0800 (CST)
JS> From: Joe Shen
JS> 1. As it's descripted in J.Abley's paper, DNS server
JS> in anycast group should be configured with a real IP
JS> on its NIC and one or two service IP on loopback
Service IP addresses also are "real IP" addresses.
JS> interface(s). BIND listen on both real IP and service
JS> IPs. Any DNS answer packet will be encapsulated with
JS> source address as service IP. To my understanding,
s/encapsulated with/sourced from/
JS> this is OK for root servers because they do not invoke
JS> recursive lookup procedure. But, if the DNS server is
JS> a member of ISP's DNS Cache server farm, recursive
JS> lookup packets to other DNS server MUST be
JS> encapsulated with real IP address.
s/encapsulated with real/sourced from unicast/
JS> Is BIND or other DNS software capable of
JS> distinguishing between DNS answer back packet and
JS> recursive lookup packets? or could this be done
JS> automatically by operating system like Solaris, Linux,
Not sure what you're asking, but it's probably OT. If I
understand you correctly, RFC 1034 or 1035 would be the place you
should start; it sounds like you're asking a protocol question.
JS> 2. If we want to design a hierachical DNS service
JS> system which distribute across multiple private AS of
JS> an ISP, is there any problem to select service IP
JS> randomly from unused address pool?
Standard routing rules apply. Think of anycast as multihoming
with a disjoint backend.
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