47 votes

Why can I traceroute to this IP address, but not ping?

On a similar question here Luke Savage explained it perfectly: Traceroute is not a protocol itself, it is an application and the protocols used depends on the implementation your are using. Primarily ...
naïveRSA's user avatar
  • 760
19 votes

Why can I traceroute to this IP address, but not ping?

To add to @naïveRSA's answer, if there's filtering/firewalling in the path one could also have the situation where an ICMP "echo reply" (ping) packet is blocked, but an ICMP "time exceeded" (tracert) ...
Arjan's user avatar
  • 331
11 votes
Accepted

Why there are ip(ip) and domain(ip) 's difference and multi rows records in the traceroute?

1) Traceroute may attempt to resolve the hop's domain name via DNS. As you didn't include any additional flags to explicitly enable this functionality, your traceroute application does so by default. ...
boomi's user avatar
  • 993
10 votes
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Traceroute UDP port question

To understand the mechanism, let's see it with an example: I issue a traceroute to 44.12.44.1 from my PC My PC sends 3 UDP datagrams to 44.12.44.1 with TLL=1 and port=33434 Inmediately sends 3 UDP ...
jcbermu's user avatar
  • 4,497
9 votes
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Slower hops in traceroute

Many routers prioritize routing packets over answering ICMP requests, they often have rate limits and queueing in place to reduce load on the router. As a result, latency on intermittent hops can be ...
Teun Vink's user avatar
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9 votes
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Why traceroute is still Used?

Traceroute doesn't give inexact information, it performs tests in a specific way and give some results based on the response it receives (or do not receive). You have to know how to interpret the ...
JFL's user avatar
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9 votes
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difference between reverse, forwarding and return path on traceroute

You are "A", you are performing a Traceroute to "B" First hop is A > R1. The response travels R1 > A. In this case, the RTT time is how long it took for the packet to get from A, to R1, and ...
Eddie's user avatar
  • 15k
9 votes

Why can I traceroute to this IP address, but not ping?

Let's look at what happens, shall we? 8.8.8.8 makes a good example, because at least from my location, I can reach it both with traceroute and ping. First let's try ping 8.8.8.8 and watch what ...
Phil Frost's user avatar
8 votes
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Private IP inside internet?

Traceroute deliberately sends packets with low time-to-live values to make the routers between you and your destination send back ICMP TTL exceeded messages. The traceroute output is basically the ...
Gerben's user avatar
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7 votes
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Is it possible to perform a Layer 2 (MAC address) traceroute?

But is there any way to do a traceroute that will show Layer 2 information? Short answer: no. Longer answer: traceroute exploits IP's TTL feature. There is no such concept in Ethernet, hence no ...
Zac67's user avatar
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6 votes
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Why does ip routing not take an even remotely direct route?

The virtual world and physical world rarely line up. Just because machines are physically close, doesn't make them logically close. Traffic goes where routing entries, and interconnects take it. Eons ...
Ricky's user avatar
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6 votes
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Whether the traceroute command only can check "to" path, can not check "back" path?

Traceroute, by its nature, only reports on the path towards the target, and very imperfectly too. You need to run traceroute from both sides to see if your routes are asymmetric. It has to be ...
jonathanjo's user avatar
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5 votes

Tips on analyzing traceroute readings

Pretty much every post I see along these lines recommends the following document: Practical Guide To (Correctly) Troubleshooting with Traceroute Traceroute can you send you down the rabbit hole, ...
dareuja's user avatar
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5 votes
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how does Trace route packet work

traceroute works by sending ICMP echo requests or fake UDP datagrams towards the destination (probes), starting with TTL set to 1 and increasing one by one. On each router/hop on the way, the packet ...
Zac67's user avatar
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5 votes
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Why there is only one hop in the tracert?

As explained by Jens Link, usually a one-hop traceroute means the host is on the same network. Since in your case, it is higly unlikely, that means you probably have a proxy that respond in place of ...
JFL's user avatar
  • 19.6k
5 votes

How to traceroute in SDN Networks while traceroute is not working in SDN by default?

One of the points of SDN is that you build a virtual "network box" where all your switching, routing, NATing, etc happens and that looks like a single device from the outside, regardless of its ...
Zac67's user avatar
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4 votes
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Tips on analyzing traceroute readings

I highly recommend the Traceroute Guide posted by dareuja. There isn't a more complete single resource on interpreting the results (that I know of, at least). Here are a few tips I've picked up over ...
Eddie's user avatar
  • 15k
4 votes

Same hop appears 4 times on a traceroute

This is due to path MTU discovery. As you can see the MTU for you first hop is 1300, while you computer expect 1500 by default. So tracepath will send several packets to determine the correct MTU, ...
JFL's user avatar
  • 19.6k
4 votes

Why there are ip(ip) and domain(ip) 's difference and multi rows records in the traceroute?

1 - it is because your traceroute client is performing reverse DNS lookup. I.E. it asks to the DNS server which is the domain name associated with this IP address. In one case, there's no such reverse ...
JFL's user avatar
  • 19.6k
4 votes
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Are traceroute hop latency measurements relative to the previous hop or to the origin?

The return times in traceroute are always relative to the sending source. Due to different ICMP handling in the hops, some returns may be slower than subsequent ones that are actually more distant. ...
Zac67's user avatar
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4 votes
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Why there still need a parenthesis contains it again in traceroute logs?

1 - By default, traceroute try to perform a reverse DNS lookup and will output the DNS name followed by the IP address in parenthesis. Many routers IP addresses don't have a PTR record, so the DNS ...
JFL's user avatar
  • 19.6k
4 votes

Is it possible to perform a Layer 2 (MAC address) traceroute?

Layer 2 information is stripped off and thrown away at every layer 3 ingress interface. A completely new layer 2 header is added on the outgoing interface. You're asking a router to do something ...
Ron Trunk's user avatar
  • 67.5k
4 votes

In a trace route, do routers that do not respond still forward the packets?

Answering ICMP requests sent to the router is a function typically performed by a router's management plane. Replying to ICMP (and at what rate) is optional. Forwarding packets is done by the ...
Teun Vink's user avatar
  • 17.3k
3 votes
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Preventing a Cisco router from appearing in a traceroute

You don't block the icmp unreachables - which are sent by your router - but the inbound packets sent by the traceroute or other tool, that have a TTL (time to live) of 1. See e.g. Cisco Guide to ...
hertitu's user avatar
  • 2,648
3 votes
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Windows implementation of traceroute (tracert)

You can't use traceroute or tracert on the same network because it counts router hops. It uses the IP TTL that is decremented by routers, but devices on the same network communicate directly, not ...
Ron Maupin's user avatar
  • 99.6k
3 votes

Windows implementation of traceroute (tracert)

Windows uses ICMP echoes for traceroute (tracert), while most *nix systems (including Cisco routers) use UDP. Note: traceroute in Linux can use ICMP with the -I option.
Ron Trunk's user avatar
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3 votes
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Are ping-times directly related to location/distance?

Not really. Yes there is certainly a correlation between ping time and distance. However there are many factors other than distance that can lead to a high ping. Congestion, crappy routing, Satellite ...
Peter Green's user avatar
  • 13.3k
3 votes

Traceroute program that does not rely on ICMP echo requests?

Traceroute (the technique) technically doesn't rely on ICMP echo requests but rather a type of ICMP unreachable. The idea is that the host sends a packet with a low TTL value and then more with ...
rnxrx's user avatar
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