Hi

In addition, to ammo's post, "Secrets of Network Cartography:
A Comprehensive Guide to nmap"[1] makes a fairly good read
about nmap.

In particular, the default timing settings (-T) are given in a
table[2].


Cheers.


[1] http://www.networkuptime.com/nmap/index.shtml
[2] http://www.networkuptime.com/nmap/page09-09.shtml