阿里云镜像站
官网下载地址:目前官网支持的版本,并没有16.04.5;如果要下载需要到ubuntu官网旧镜像版本下载地址
PXE
https://help.ubuntu.com/community/Installation/LocalNet
https://help.ubuntu.com/community/Installation#Server_and_network_installations
https://help.ubuntu.com/community/Installation
https://help.ubuntu.com/lts/installation-guide/example-preseed.txt
https://help.ubuntu.com/lts/installation-guide/s390x/apbs02.html