-e TZ=${TZ:-Europe/Amsterdam}`# optional` `# specify a timezone to use, see this [list](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones#List).` \
-e SUBDOMAINS=subdomain1,subdomain2 `# multiple subdomains allowed, comma separated, no spaces, if your domain is user.duckdns.org you put user, not a sub-subdomain` \
-e UPDATE_IP=ipv4 `# optional` `# Set to `ipv6` or `ipv4` to update **only** your public IPv4/6 address. Set to `both` to update IPv6 and IPv4 address. This variable makes use of a [third-party service](#notice-regarding-automatic-detection). Omitting this variable uses DuckDNS for detection and only supports IPv4. `both` and `ipv6` modes needs [host networking](#networking-net).` \