How to get DNS zone files of my domains

The best way to retrieve DNS zone files is through the CLI and utilizing the Linode APIv4..

The following command will give a list of the domain IDs:

curl -sH "Authorization: Bearer $TOKEN"  https://api.linode.com/v4/domains | jq | grep -i 'id\|domain' | grep 1 | awk -F':' '{print $2}' | tr ',' ' '

The following loop can be used to read in all the of domain IDs:

for i in ID1 ID2 IDN; do linode-cli domain records-view $i; done

The above portion can be modified to echo the IDs to a .txt file or really whatever file you'd like.

I would also recommend taking a look at this Community Questions Site post regarding DNS zones: How to retrieve/save all DNS records?