[atlas] 1msec RTT to ipv6.google.com?

Hi

I've been reviewing both paths and indeed 2a00:1450:4004:801::200e is 1msec away from the probe (it is answered right at the internet exchange premises by either Google's router or a colocated server/cache) while 2a00:1450:4004:806::200e has to go out to Google DCs hence the ~12msec. 

Thank you all for your help.

AA

-----Original Message-----
From: ripe-atlas [mailto:ripe-atlas-bounces at ripe.net] On Behalf Of Robert Kisteleki
Sent: Tuesday, 21 de July de 2015 12:55
To: Roman Mamedov; Jen Linkova
Cc: ripe-atlas at ripe.net; Tomáš Hetmer
Subject: Re: [atlas] 1msec RTT to ipv6.google.com?


> From the original message:
> 
>> I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT
>> RTT I get on the CPE the probe is connected to
>>    0 2a00:1450:4003:806::200e                   56  59 12ms  echo reply
> 
> My guess is that maybe the probe was set up to use a different DNS resolver
> than the CPE, and it got a different IPv6 instead of 2a00:1450:4003:806::200e.

Indeed the probe pinged 2a00:1450:4004:801::200e and not the address above.
I have no idea if that's the root cause for this, but it's certainly a
different target. It could be the same DNS resolver but it got different
answers at different times?

I set up one-off traceroutes 2144086 (ICMP) and 2144089 (UDP) and they seem
quite reasonable to me (5 hops, ~1.2ms to target).

Robert