Labs 5.4 and 5.6

Hi all,

I have followed Labs manual step by step and install all necessary software but I found the error as below:

//snip//

• Labs 5.4

root@serv01:/etc/bind# ssh -X 192.168.1.3 xeyes
Error: Can't open display:

• Labs 5.6
• root@serv01:/etc/bind# vncviewer localhost:1

TigerVNC Viewer 64-bit v1.10.1
Built on: 2020-04-09 06:49
Copyright (C) 1999-2019 TigerVNC Team and many others (see README.rst)
See https://www.tigervnc.org for information on TigerVNC.
Can't open display:
root@serv01:/etc/bind#

//snip//

Anyone know the issue?

Thank you.