Technical data

traceroute
-a
If the destination host has multiple addresses, traceroute probes all addresses if
this option is set. Normally, only the first address as returned by the resolver is
attempted.
-c stoptime
Specifies a delay (in seconds) to pause between probe packets. This can be
necessary if the final destination is a router that does not accept undeliverable
packets in bursts.
-f
Disables IP fragmentation. If the given packet size is too big to be handled
unfragmented by a machine along the route, a ‘‘fragmentation needed’’ status is
returned, and the indicator !F is printed. If a gateway returns the proper MTU
size to be used,
traceroute automatically decreases the packet size to this new
value. If the proper MTU size is not returned,
traceroute chooses a smaller
packet size.
-g gateway
Enables the IP LSRR (loose source record route) option. This is useful for asking
how somebody at the specified gateway reaches a particular target.
-h server
Specifies the name or IP address of the whois server that is contacted for the
AS-number lookup, if the -A option is given.
-i initial_ttl
Sets the starting time-to-live value to initial_ttl , to override the default value
of 1. Effectively this skips processing for intermediate hosts that are less than
initial_ttl hops away.
-k
Keeps the connection to the
whois server permanently open. This speeds lookups
considerably, because a connection setup for each individual lookup is not
necessary. However, not all whois servers support this feature.
-l
Prints the value of the TTL field in each packet received. (This flag can be used
to help detect asymmetric routing.)
-m max_ttl
Sets the maximum time-to-live (maximum number of hops) used in outgoing
probe packets. The default is 30 hops, which is the same default used for TCP
connections.
-N
Displays the network name for each hop. If a BIND resolver cannot be reached,
network names are retrieved just from the /etc/networks file.
-n
Displays the hop IP addresses using dotted-decimal notation. This saves a
name server address-to-name lookup for each gateway found on the path. It
also prevents a reverse lookup for numeric dotted-quad addresses given on the
command line, such as destination host or -g gateway addresses.
Troubleshooting Utilities Reference A–49