DNS Server Latency discrepancy in Azure Australia Southeast


#1

Whilst configuring some new Azure servers this afternoon, I’ve noticed a significant discrepancy in latency between 1.1.1.1 and 1.0.0.1 from an Azure machine in the Australia Southeast region.

When pinging 1.1.1.1 we get an unexpectedly high latency of ~250ms. When pining 1.0.0.1 we get an expected ~1m of latency.

I can’t successfully get a traceroute from the machine I’m on to 1.1.1.1 or 1.0.0.1, Azure may be tampering with the ICMP packets, so I will update this post if I am able to determine what the cause of this is and get an accurate traceroute to both.

I’ve been able to reproduce this with two different Azure VMs in the same region in different vnets and security groups.

We don’t rely on 1.1.1.1 for our Azure VMs, so no urgency on our end, was just an interesting observation I thought I’d pass on.

Cheers,
Josh

Pings

Ping to 1.1.1.1:

Pinging 1.1.1.1 with 32 bytes of data:
Reply from 1.1.1.1: bytes=32 time=252ms TTL=45
Reply from 1.1.1.1: bytes=32 time=252ms TTL=45
Reply from 1.1.1.1: bytes=32 time=252ms TTL=45
Reply from 1.1.1.1: bytes=32 time=252ms TTL=45

Ping statistics for 1.1.1.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 252ms, Maximum = 252ms, Average = 252ms

Ping to 1.0.0.1:

Pinging 1.0.0.1 with 32 bytes of data:
Reply from 1.0.0.1: bytes=32 time=1ms TTL=56
Reply from 1.0.0.1: bytes=32 time<1ms TTL=56
Reply from 1.0.0.1: bytes=32 time<1ms TTL=56
Reply from 1.0.0.1: bytes=32 time=1ms TTL=56

Ping statistics for 1.0.0.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms

#2

Looks like 1.1.1.1 is being routed to Ashburn, whilst 1.0.0.1 is being routed to Melbourne.

> nslookup -vc -class=chaos -type=txt id.server 1.1.1.1
Server:  1dot1dot1dot1.cloudflare-dns.com
Address:  1.1.1.1

Non-authoritative answer:
id.server       text =

        "iad02"
> nslookup -vc -class=chaos -type=txt id.server 1.0.0.1
Server:  1dot1dot1dot1.cloudflare-dns.com
Address:  1.0.0.1

Non-authoritative answer:
id.server       text =

        "mel01"