Aide pour installation de ns2 sur ubuntu

bonjour à tous j'ai probleme pour l'installation de ns2 sur ubuntu quand je fini les differentes etapes d'installation et que le tape ns dans mon terminal voici le message qui s'affiche:
Usage: host [-v] [-a] [-t querytype] [options] name [server]
Listing: host [-v] [-a] [-t querytype] [options] -l zone [server]
Hostcount: host [-v] [options] -H [-D] [-E] [-G] zone
Check soa: host [-v] [options] -C zone
Addrcheck: host [-v] [options] -A host
Listing options: [-L level] [-S] [-A] [-p] [-P prefserver] [-N skipzone]
Common options: [-d] [-f|-F file] [-I chars] [-i|-n] [-q] [-Q] [-T] [-Z]
Other options: [-c class] [-e] [-m] [-o] [-r] [-R] [-s secs] [-u] [-w]
Special options: [-O srcaddr] [-j minport] [-J maxport]
Extended usage: [-x [name ...]] [-X server [name ...]]