When you ping a host or server to test connection ,you notify that 50 % of packets had lost! What does this mean?

Dear Bekhouche Liamine,

First i am not sure either you are pinging any host or server inside your local network, means behind the switch and you are using local ip's. if this is the case then you need to perfrom different things like check if only one local host is facing this issue or most of them iside your local network. also you need to check the usage of your switch, issue might be inyour switch.

you can check the process of your switch, below10% is reasonable but should be5 or less is good. if there is any loop created inside your network it will easly bring down your whole network by consuimg all the resourse and keeps sending infinite broadcast messages.

you can also check the port of your switch on which the host is connected try changing it and then do the ping test again

if you host is on some other location, not in the same office, then it is wan issue. try to do the tracerouter. and see where the latency is high. you can report this to your isp to check the connection and use some other route to fix it. 

tracroute you can perfrom on your raouter. tracert you can use on your pc.

hope this will help you. if some thing else do let me know

regards

Ali