Sending basic PDU in Packet Tracer continues indefinitely?

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

Hi, sending a basic PDU in Packet Tracer just continues indefinitely - why is this? I've created a video.


If I just leave it it will continue forever.
As you can tell i'm just a beginner student but I'd like to know why? My rather useless teacher can't advice me.