Understanding Pathping / Tracert

Whenever I do a tracert from DOS to google.com I see something like this:

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?

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?

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 ________________________________________