====== CDN Commands ======
I want to take a note here for all commands we met when running a CDN service.

===== nslookup =====
  - ''nslookup www.simplenature.cn''
  - ''nslookup -type=cname www.simplenature.cn''
  - ''nslookup -type=mx simplenature.cn''
  - ''nslookup -q=txt simplenature.cn''

===== dig =====
  - ''dig www.simplenature.cn''
===== wget =====
  * ''wget -S "http://xxxxx"''
  * ''wget -S "https://xxxx" -e --http_proxy=114.123.11.11''
  * ''wget -S "http://cname.domain" --header=host:domain''
===== curl =====
  * ''curl -voa "http://xxxx"''
  * ''curl -voa "http://xxxx" -x "114.123.11.11"''
  * ''curl -voa "http://xxxx.cname.domain/xxx" --header "host:domain"
''
===== systemctl =====
  * systemctl status elasticsearch.service -l
  * systemctl enable elasticsearch
  * systemctl stop elasticsearch
  * systemctl disable elasticsearch
  * systemctl start elasticsearch
  * systemctl restart elasticsearch

===== journalctl =====
  * journalctl -u elasticsearch