43
43
based on these values. A lower score is better, in the end it prints
44
44
one line showing the server with the best score.
46
If the DNS name has multiple IP addresses associated with IT
48
will test each of the IP addresses independently. In this case,
70
76
nothing got through at all. That indicates that either the host doesn't
71
77
exist, or it is down.
81
\fB#\fR netselect \-vv http.us.debian.org
87
204.152.191.39 300 ms 17 hops 90% ok ( 9/10) [ 899]
88
35.9.37.225 9999 ms 30 hops 0% ok
89
64.50.233.100 9999 ms 30 hops 0% ok
90
128.30.2.36 183 ms 15 hops 90% ok ( 9/10) [ 510]
91
149.20.20.135 226 ms 18 hops 90% ok ( 9/10) [ 702]
95
In this case, since the single name has multiple DNS addresses all of the
96
servers will be tested indenpendently and the fastest server will be provided.
98
If you notice the above output you will see that the time for some hosts
99
is 9999 ms. This is typically an indication of remote hosts blocking the
102
relies on. To prevent this issue you can use ICMP tests. For example,
103
repeating the above test using ICMP, that is:
106
\fB#\fR netselect \-I \-vv http.us.debian.org
109
yields the following output:
112
204.152.191.39 291 ms 17 hops 100% ok (10/10) [ 785]
113
35.9.37.225 180 ms 19 hops 66% ok ( 2/ 3) [ 783]
114
64.50.233.100 140 ms 12 hops 100% ok (10/10) [ 308]
115
128.30.2.36 182 ms 15 hops 100% ok (10/10) [ 455]
116
149.20.20.135 227 ms 18 hops 100% ok (10/10) [ 635]
120
In this last example the selected server will change since, actually, the
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fastest server is one that also actively blocks UDP probes.
114
165
The more packets you use, the more accurate are the results... and the
115
166
longer it takes to run. The default is 10, which is usually okay.
170
Use ICMP instead of UDP probes. In some occassions (firewalled hosts)
171
UDP probes like those used in
173
will get filtered out and hosts might be perceived as dead. Using this
176
use ICMP probes instead.
119
180
.BR traceroute (8),