How to correct the network route problem

Issue

• Ip addresses:

  Interface  Slave Of  IPv4 Address        MTU     State  MAC Address
  =========  ========  ==================  ======  =====  =================
  lo         -         127.0.0.1/8         16436   up     -
  em1        -         10.11.50.1/24       1500    up     bc:30:5b:f3:3a:xx
  em2        -         192.168.165.0/24    1500    up     bc:30:5b:f3:3a:yy
  em3        -         -                   1500    DOWN   bc:30:5b:f3:3a:zz
  em4        -         -                   1500    DOWN   bc:30:5b:f3:3a:aa
  tun0       -         10.8.0.1            1500    up     -

• routing table

[root@test ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.165.0   0.0.0.0         255.255.255.0   U     0      0        0 em2
10.11.50.0      0.0.0.0         255.255.255.0   U     0      0        0 em1
10.11.0.0       0.0.0.0         255.255.255.0   U     0      0        0 em1
0.0.0.0        192.168.165.1    0.0.0.0         UG    0      0        0 em2

• It does not work when specifying dev in route add command.

route add -net 10.11.0.0 netmask 255.255.255.0 em1