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Type the Name or IP address of the host you want to trace to and press Return.

Network routes are traced by sending a packet with successively larger time to live (TTL) values in the IP header and recording any "time limit exceeded" messages that are returned. As each router forwards a packet, it decrements the TTL value and discards the packet reporting an error if TTL reaches zero. Each hop is tried three times and the average round trip time is displayed in seconds.

Normally a trace terminates when trace route receives a "Port unreachable" response from the target host. If trace route receives a "Destination unreachable" response that is not "Port unreachable" from the target host, trace route will show "!dest" in the Received column, show the reason the packet could not be forwarded in the Name column, and terminate the trace.

When a "time limit exceeded" message is received, trace route uses the source address of this message to lookup the corresponding Name. The trace continues while any lookup is in progress as indicated by the word "Looking..." in the Name column.

"UDP Trace" is similar to the standard UNIX "traceroute" tool.

"ICMP Trace" uses ICMP echo requests instead of UDP datagrams for tracing similar to the Windows "tracert" tool. This may work better through some firewall devices.

"TCP Trace" uses a TCP connection request to the specified port (in the preferences drawer) to identify where the corresponding port is blocked. Each successive router that returns a "time limit exceeded" message is assumed to pass the connection request normally. If an intermediate firewall rejects the connection request, the received column will show "!reach". If the request is dropped so there is no response to the TCP probe (red X), the corresponding TTL is probed again using an ICMP echo request (ping) to identify the hop that blocked the original request. Thus you might see two check marks or X's in the sent and received columns. The first mark is for the TCP probe. The second if present is for an ICMP echo request. A green check indicates some response was received. A red X means there was no response. TCP Trace assumes the route is stable and may provide more information if the target responds to ping. TCP Trace is useful for determining which device is blocking a specific connection request, or may be used to provide trace route information when other methods are blocked.

"Record Route" (sends an ICMP echo request with the IP Record Route option (RR) telling each router along the path to add its own IP address to the option data. Up to nine IP addresses can be recorded in the IP header before running out of space. This option may reveal alternate router addresses or allow you to trace through devices that do not otherwise respond.

You can specify a Hop Limit and whether to resolve names in the Trace Route preferences drawer.

### Additional Features

When you invoke one window from another, the corresponding data is automatically transferred.

A popup menu keeps a list of Recent Targets or history pre-loaded with some common values based on your network configuration. The contents of the target field are added to the list when a test to that target is invoked. If the recent targets menu becomes full (10 entries), the least recently used item will be removed. To add or remove an item, or clear the entire list, use the corresponding selections from the History menu.

You can double-click on any destination in the table to start a Ping test to that address. You don't have to wait for the trace to finish.

You can select the results of a Trace Route test and copy them to the clipboard as plain text (for pasting into email messages). If you include the first row of the table in your selection, the table headings will also be copied.

IPNetMonitorX recognizes the 'GURL' AppleEvent to handle URLs of the form:

traceroute://www.sustworks.com;type=ICMP

You can select File->Save to save a double-clickable ".ipnm" document with the corresponding URL. You can preview the URL that will be saved by pausing over the "Save" button in the panel that appears. URLs are saved as plain text. You can include multiple URLs in the same file, one per line, to open the corresponding tools.

You can open and use multiple Trace Route windows at the same time.

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