Understanding Pathping / Tracert

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Whenever I do a tracert from DOS to google.com I see something like
this:
1     5ms     3ms     3ms     192.168.0.1
2      *           *          *          Request Timed Out

The 2nd hop always times out, no matter what site I tracert. I'm
trying to understand what this 2nd hop represents, is it the external
side of my dlink router which is timing out, or is this my ISP that is
timing out? One reason I'm curious is because whenever I do a pathping
to any site, the pathping ends on the 2nd hop, it never gets any
further. Pathping is a great tool, why wont it work properly for me
here?

Any thoughts?


Understanding Pathping / Tracert
Whenever I do a tracert from DOS to google.com I see something like
this:
1     5ms     3ms     3ms     192.168.0.1
2      *           *          *          Request Timed Out

The 2nd hop always times out, no matter what site I tracert. I'm
trying to understand what this 2nd hop represents, is it the external
side of my dlink router which is timing out, or is this my ISP that is
timing out? One reason I'm curious is because whenever I do a pathping
to any site, the pathping ends on the 2nd hop, it never gets any
further. Pathping is a great tool, why wont it work properly for me
here?

Any thoughts?


Re: Understanding Pathping / Tracert
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Have you tryed removing the router and just pinging it from your
computer. My service provider has limited each custmer to one IP
unless you request to have two. Are you using asigned IP's on your
Dlink or are you using DHCP from the router 192.168.0.1?


Re: Understanding Pathping / Tracert
Your Internet service providor's router connecting you may not respond to
the ICMP messages of a traceroute as a security feature.

Routers can be configured to not reply to ICMP messages.  In a firewall or
semi-firewall-like device, this is normally set to reduce denial of service
attacks or network information gathering.  This may be the case on your
DLink router which may have some built in features like this.  It would be
expected of a small consumer router that is intended for use on the Internet
without all of the confusion of every configurable parameter possible.

The IP addresses shown in a traceroute will usually represent the interface
of routers facing your path on the network/Internet.  The first line of your
traceroute, 192.168.0.1, is very likely your DLink router inside interface.
The second line of the traceroute will be the next router, the closest
router to you in your Internet service provider.

ICMP has several types of network traffic with your traceroute/pathping as
just one of them.  A router could be, as an example, configured to respond
to successful PINGs, respond to successful traceroutes, but not reply to
PINGs to unreachable addresses or when the TTL (time to live on the IP
packet) expires.  Look into how a traceroute works: by sending packets with
an intentional TTL of 1 then 2 then 3 and so on.  This causes each router in
the path to look at the IP packet TTL and either decrease the TTL and send
it onward or drop the packet and send an ICMP message to the host which sent
it.  This is how a host determines the routers along the path.  By the way,
the TTL of an IP packet and the behaviour of routers reducing that value in
the packet eliminates packets floating forever in the event that a looping
path occurs in networks.

Reference this list of ICMP message types:
Type    Name                    Reference
----    -------------------------        ---------
  0    Echo Reply                 [RFC792]
  1    Unassigned                    [JBP]
  2    Unassigned                    [JBP]
  3    Destination Unreachable             [RFC792]
  4    Source Quench                  [RFC792]
  5    Redirect                 [RFC792]
  6    Alternate Host Address                [JBP]
  7    Unassigned                    [JBP]
  8    Echo                     [RFC792]
  9    Router Advertisement            [RFC1256]
 10    Router Solicitation            [RFC1256]
 11    Time Exceeded                 [RFC792]
 12    Parameter Problem             [RFC792]
 13    Timestamp                 [RFC792]
 14    Timestamp Reply                 [RFC792]
 15    Information Request             [RFC792]
 16    Information Reply             [RFC792]
 17    Address Mask Request                     [RFC950]
 18    Address Mask Reply             [RFC950]
 19    Reserved (for Security)               [Solo]
 20-29    Reserved (for Robustness Experiment)        [ZSu]
 30    Traceroute                [RFC1393]
 31    Datagram Conversion Error        [RFC1475]
 32     Mobile Host Redirect              [David Johnson]
 33     IPv6 Where-Are-You                 [Bill Simpson]
 34     IPv6 I-Am-Here                     [Bill Simpson]
 35     Mobile Registration Request        [Bill Simpson]
 36     Mobile Registration Reply          [Bill Simpson]
 37     Domain Name Request                     [RFC1788]
 38     Domain Name Reply                       [RFC1788]
 39     SKIP                                    [Markson]
 40     Photuris                                [RFC2521]
 41     ICMP messages utilized by experimental  [RFC4065]
        mobility protocols such as Seamoby
 42-255 Reserved                    [JBP]

     ===========
     Scott Perry
     ===========
Indianapolis, Indiana
________________________________________


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