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Evgeniy Pozdnyakov avatar Server

Why traceroute with different arguments makes different routes?

cn flag
Evgeniy Pozdnyakov

I was studying how traceroute works and now im feeling kinda stuck.

sudo traceroute -T aws.com
traceroute to aws.com (13.227.211.129), 30 hops max, 60 byte packets
 1  * * *
 2  100.64.0.103 (100.64.0.103)  0.546 ms 100.64.0.72 (100.64.0.72)  0.664 ms 100.64.0.33 (100.64.0.33)  0.650 ms
 3  130.193.63.248 (130.193.63.248)  3.796 ms  32.932 ms  3.887 ms
 4  mow-b4-link.ip.twelve99.net (62.115.170.18)  4.927 ms  4.866 ms  4.891 ms
 5  * * *
 6  adm-bb3-link.ip.twelve99.net (62.115.136.151)  43.684 ms  43.465 ms  43.854 ms
 7  adm-b2-link.ip.twelve99.net (80.91.253.163)  43.548 ms adm-b2-link.ip.twelve99.net (62.115.141.67)  43.077 ms adm-b2-link.ip.twelve99.net (80.91.253.163)  42.585 ms
 8  a100-ic314746-adm-b2.ip.twelve99-cust.net (62.115.146.67)  44.687 ms a100row-ic300134-adm-b2.ip.twelve99-cust.net (213.248.87.114)  48.243 ms  48.218 ms
 9  * 54.239.114.36 (54.239.114.36)  42.782 ms *
10  54.239.114.147 (54.239.114.147)  47.749 ms 54.239.114.65 (54.239.114.65)  41.303 ms 54.239.114.69 (54.239.114.69)  41.403 ms
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  150.222.249.245 (150.222.249.245)  42.581 ms 52.93.130.127 (52.93.130.127)  43.424 ms 54.239.42.203 (54.239.42.203)  42.566 ms
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  server-13-227-211-129.ams54.r.cloudfront.net (13.227.211.129)  45.159 ms  46.248 ms  49.153 ms

What are these *** hops? Is every hop that marked *** a independent router? Or it might trying to reach same router a couple times, so couple hops will be meaning same router but we will never know? Or my packets might running in circles and, for example, couple of hops might be the same router?

sudo traceroute -I aws.com
traceroute to aws.com (65.9.77.126), 30 hops max, 60 byte packets
 1  * * *
 2  100.64.0.73 (100.64.0.73)  0.494 ms  0.499 ms  0.494 ms
 3  130.193.63.248 (130.193.63.248)  3.903 ms  3.853 ms  3.847 ms
 4  mow-b4-link.ip.twelve99.net (62.115.170.18)  3.649 ms  3.701 ms  3.643 ms
 5  * * *
 6  adm-bb3-link.ip.twelve99.net (62.115.136.151)  43.460 ms  42.995 ms  42.980 ms
 7  adm-b2-link.ip.twelve99.net (213.155.137.211)  42.948 ms  42.850 ms  42.850 ms
 8  a100row-ic300134-adm-b2.ip.twelve99-cust.net (213.248.87.114)  51.693 ms  51.568 ms  51.557 ms
 9  54.239.114.84 (54.239.114.84)  46.527 ms  46.006 ms *
10  52.93.112.61 (52.93.112.61)  45.692 ms  45.704 ms  45.521 ms
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  65.9.77.126 (65.9.77.126)  45.380 ms  45.436 ms  45.392 ms

Now i added -I to use ICMP packets. Why route is different? Is that BGP working?

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berndbausch avatar
us flag
berndbausch
`***` means that the router doesn't send anything back, at least not on time. I guess there are routing alternatives; you don't always get the same route.
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Evgeniy Pozdnyakov avatar
cn flag
Evgeniy Pozdnyakov
the question is: why i dont get the same route? is that because of Border Gateway Protocol (BGP) working?
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Nikita Kipriyanov avatar
za flag
Nikita Kipriyanov
This is meaningless statement. Any routing in the world works because of BGP. What is more interesting, that there could be different routes due to channel load balancing somewhere, QoS may be set up in such a way that it runs packets with different properties via different routes and so on. The question is so general so it couldn't be answered. Can you be (a lot) more concrete? We are solving business problems here, not answering to general questions. What is the specific problem you are solving?
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Evgeniy Pozdnyakov avatar
cn flag
Evgeniy Pozdnyakov
This is meaningless answer. The question was: why I'm getting different routes and it was stated. Actually, i just didnt pay to much attention at ip address that was resolved, that was a key to my question.
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Evgeniy Pozdnyakov avatar
cn flag
Evgeniy Pozdnyakov
Also, i didnt know serverfault is all about so-called "business problems", i must apologize. "Business problems" is all about [how ipv4 subbnetting work](https://serverfault.com/questions/49765/how-does-ipv4-subnetting-work) or [can i mount switch upside down](https://serverfault.com/questions/384397/can-you-mount-a-network-switch-upside-down), no doubt.
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Score:1
avatar Server
vn flag
Mark Wagner

It has nothing to do with traceroute options or BGP. The route is different because aws.com resolves to multiple IPs. For you, at least 13.227.211.129 (first traceroute) and 65.9.77.126 (second traceroute).

For me it resolves to:

aws.com has address 52.84.169.36
aws.com has address 52.84.169.63
aws.com has address 52.84.169.32
aws.com has address 52.84.169.117
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George Y avatar Server
vn flag
George Y

You already know the answer:

-T means establishing TCP connection to 80 port, whilst -I means sending ICMP packets to 53 udp port. Some routers forbid ICMP packets for self-protection. So it could be different.

Even when you try TCP connection for several times, it could be different too. Because the whole internet is like a road net, and each router is like a traffic intersection. You cannot guarantee to drive to the same location via the the same route each time, can you?

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