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I know that asterisks mean that the router didn't send the ICMP message back saying that TTL was 0 and I had to dump the request.

but sometimes for some cases when I want to check for the path of my packets to a server, at some point it keeps printing * * * and never ends. Even when I set -h flag (or -m flag depending on your operating system) to 255 which is the maximum number of TTL, it keeps printing asterisks to the end, I mean clearly my packet doesn't need to take 255 hops to the destination.

Here is an example for microsoft.com

tracert -h 255 microsoft.com Tracing route to microsoft.com [40.76.4.15] over a maximum of 255 hops: 1 125 ms 127 ms 144 ms 10.10.10.232 2 148 ms 151 ms 125 ms 149.202.66.253 3 122 ms 129 ms 123 ms 10.50.60.61 4 139 ms 128 ms 127 ms 10.17.130.102 5 123 ms 125 ms 125 ms 10.73.0.6 6 150 ms 132 ms 134 ms 10.95.33.10 7 135 ms 131 ms 133 ms be100-1112.ams-5-a9.nl.eu [213.251.128.67] 8 160 ms 181 ms 181 ms ams-ix-2.microsoft.com [80.249.209.21] 9 169 ms 187 ms 131 ms ae25-0.icr02.ams21.ntwk.msn.net [104.44.239.77] 10 210 ms 210 ms 208 ms be-122-0.ibr02.ams21.ntwk.msn.net [104.44.22.245] 11 224 ms 218 ms 205 ms be-11-0.ibr02.lon24.ntwk.msn.net [104.44.16.2] 12 211 ms 208 ms 214 ms be-1-0.ibr02.lon22.ntwk.msn.net [104.44.16.57] 13 205 ms 211 ms 219 ms be-7-0.ibr02.nyc30.ntwk.msn.net [104.44.18.154] 14 211 ms 216 ms 211 ms 104.44.28.55 15 203 ms 224 ms 219 ms ae162-0.icr02.bl20.ntwk.msn.net [104.44.21.234] 16 * * * Request timed out. 17 * * * Request timed out. 18 * * * Request timed out. 19 * * * Request timed out. 20 * * * Request timed out. 21 * * * Request timed out. 22 * * * Request timed out. 23 * * * Request timed out. 24 * * * Request timed out. 25 * * * Request timed out. 26 * * * Request timed out. 27 * * * Request timed out. 28 * * * Request timed out. 29 * * * Request timed out. 30 * * * Request timed out. 31 * * * Request timed out. 32 * * * Request timed out. 33 * * * Request timed out. 34 * * * Request timed out. 35 * * * Request timed out. 36 * * * Request timed out. 37 * * * Request timed out. 38 * * * Request timed out. 39 * * * Request timed out. 40 * * * Request timed out. 41 * * * Request timed out. 42 * * * Request timed out. 43 * * * Request timed out. 44 * * * Request timed out. 45 * * * Request timed out. 46 * * * Request timed out. 47 * * * Request timed out. 48 * * * Request timed out. 49 * * * Request timed out. 50 * * * Request timed out. 51 * * * Request timed out. 52 * * * Request timed out. 53 * * * Request timed out. 54 * * * Request timed out. 55 * * * Request timed out. 56 * * * Request timed out. 57 * * * Request timed out. 58 * * * Request timed out. 59 * * * Request timed out. 60 * * * Request timed out. 61 * * * Request timed out. 62 * * * Request timed out. 63 * * * Request timed out. 64 * * * Request timed out. 65 * * * Request timed out. 66 * * * Request timed out. 67 * * * Request timed out. 68 * * * Request timed out. 69 * * * Request timed out. 70 * * * Request timed out. 71 * * * Request timed out. 72 * * * Request timed out. 73 * * * Request timed out. 74 * * * Request timed out. 75 * * * Request timed out. 76 * * * Request timed out. 77 * * * Request timed out. 78 * * * Request timed out. 79 * * * Request timed out. 80 * * * Request timed out. 81 * * * Request timed out.
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  • How is tracert supposed to know 255 is "clearly" too many hops for the packet to reach its destination? Tracert has nothing else to do than to try the next TTL value like it's programmed to do? If you tell it to try up to 255 hops, then why shouldn't it go to the end? Commented Jul 21, 2020 at 14:19

1 Answer 1

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This has been increasingly common over the past decade as more and more network administrators decide that black-holing ICMP traffic is a good idea (whether or not it is is out of scope of this answer). Because traceroute uses ICMP traffic, when it encounters a node which does not accept or respond to them, it appears in the report that the host doing so is timing out.

As a result, newer tools such as mtr have become available which do effectively the same thing that traceroute does, but using TCP packets rather than ICMP packets.

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