Slaves or Forwarders?

Mark Andrews marka at
Tue Aug 23 22:00:43 UTC 2016

In message <844475874024407090c1c2e9d5718297 at>, "Darcy Kevin
 (FCA)" writes:
> From an InfoSec standpoint, of course one would prefer to use
> cryptographic methods of securing DNS data, but, in the absence of that,
> slaving could, arguably, be considered more secure than forwarding, in
> the sense that forwarding usually generates more network transactions,
> over time, for any given resolution of any given name, and thus more
> chances for a bad guy to successfully spoof a response and have that
> forged answer be cached.
> One could also eke out a small measure of extra security (again, if
> cryptographic methods are for some reason unavailable) by turning off
> IXFR and thus causing all zone transfers to occur with AXFR, which is
> TCP-based and thus presumably harder to spoof. But, that's a heavy price
> to pay for a small increment of extra security. Better to go for crypto,
> at that point, either within the DNS protocol itself (e.g. TSIG, DNSSEC),
> by implementing (as many have) an out-of-band method of replicating zone
> data (e.g. rsync-over-ssh, Infoblox-style "grid replication" over OpenVPN
> tunnels) or by securing *all* communicati on between nameserver instances
> (e.g. IPSEC tunnels).

named only accepts IXFR over TCP.  While the protocol supports sending
deltas with IXFR/UDP named does not use that part of the protocol.
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at

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