networking - how to stop eth0 bridged connection via eth1 host only connection in a virtual machines?

I have to simulate unplugged network cable for testing issue to all applications we are developing in my company .
I have about 6 virtual machines Cent-OS on a virtual box .
from a php web page , I have to choose a server and stop its network and then start it again .
of course I'm using ssh for remote connection to other servers .
and I if I stopped the eth0 (main network) on a server . I won't be able to reach it again with ssh .
so I had to find another way to perform this .
I made another network connection (Host-only) between servers via virtualbox with the help of this tutorial , then I logged into one of the servers to configure IP for this new network with these two commands :

 sudo ifconfig eth1 192.168.1.101 up 

also

sudo ifconfig eth1 inet 192.168.1.101 broadcast 192.168.1.255 netmask 255.255.255.0 up   

but when I'm trying to ssh this via php :

exec('ssh root@192.168.1.101 2>&1; ',$output);

I get this output :

ssh: connect to host 192.168.1.101 port 22: No route to host

I don't know what I have missed ?

Edit : This is what I get when I run route

$ route -n                                                                                                        
Kernel IP routing table                                                                                                               
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface                                                         
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1                                                          
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0                                                          
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0                                                          
0.0.0.0         192.168.0.204   0.0.0.0         UG    0      0        0 eth0