trace route shows private IP range after router

[Justinh]

I don't understand why trace route is showing 10.x.x.x (entire address range is private, right?) after the router, which goes to a pass-thru cable modem. How can this be?

Tracing route to cnn.com [151.101.67.5]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms RT-AC68P-D9B8 [192.168.1.254]
2 20 ms 18 ms 20 ms 10.198.96.1
3 21 ms 19 ms 20 ms 172.30.31.129 <-- my ISP's address block
4 25 ms 34 ms 28 ms 10.16.64.89
5 25 ms 27 ms 37 ms 10.16.64.5
6 28 ms 27 ms 34 ms 68-66-73-220.client.mchsi.com [68.66.73.220]
7 27 ms 27 ms 26 ms po10.atlga001er1.mchsi.com [68.66.72.29]
8 25 ms 25 ms 27 ms 157.52.127.116
9 30 ms 16 ms 13 ms 151.101.67.5

 

[ColinTaylor]

Perfectly normal. Internal ISP routing. 172.30.31.129 is a private address just like 10.16.64.89 is.

Private network - Wikipedia

en.wikipedia.org

 

[Justinh]

Right, I didn't closely look at the 172.x address. Those hops really surprise me - didn't realize that kind of thing happened. Thank you.

 

[Deepcuts]

Private IP 1st hop after your router means most likely you have a PPPoE connection.
I would say impossible without PPPoE and a public IP (no CGNAT)