[c-nsp] IPv6 domain reply Cisco 6509 IPv4 address

Chuck Church chuckchurch at gmail.com
Thu Aug 16 10:09:15 EDT 2012

Weird.  I'm just starting to play around with Juniper stuff now, and noticed
pretty much the same behavior.  Configured a v4 DNS server, but a lookup
resulted in a V6 address trying to be used.  Don't have V6 enabled anywhere,
routing table was empty.  Figured it was some knob I'm not familiar with in
JunOS.  Didn't get to wiresharking it, but similar.  Would a device be silly
enough to request an AAAA record out a v4 only interface?  Would a DNS
server ever hand out an AAAA for a v4 request (perhaps NAT64/DNS64
intercepting somewhere?)  


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Chris Lane
Sent: Thursday, August 16, 2012 9:41 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] IPv6 domain reply Cisco 6509 IPv4 address

We do not run IPv6 currently from this site, ipv6 is not enabled on box.
when i ping google.com i get the following response.
ping google.com
Translating "google.com"...domain server ( [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:4860:4001:800::100E, timeout is 2

% No valid source address for destination

Rev is:
and also for further IPV6 analysis:
sh ipv6 int
LI-Null0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::218:74FF:FE16:D180
  No global unicast address is configured
  Joined group address(es):
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ND DAD is not supported
  ND reachable time is 30000 milliseconds

Ran this by a friend yesterday who also found this strange behavior and at
quick glance couldn't find any bugs related to rev.

Just wondering if anyone else sees this behavior?


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