Can not install last version

Try to install whois app inside docker container (based on Laradock) Getting output:

root@475f4c9d3438:/var/www# apt-get install whois
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libargon2-0 libicu64
Use 'apt autoremove' to remove them.
The following NEW packages will be installed:
  whois
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 34.0 kB of archives.
After this operation, 184 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 whois amd64 5.2.11 [34.0 kB]
Fetched 34.0 kB in 1s (28.1 kB/s)
Selecting previously unselected package whois.
(Reading database ... 25664 files and directories currently installed.)
Preparing to unpack .../whois_5.2.11_amd64.deb ...
Unpacking whois (5.2.11) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up whois (5.2.11) ...

But 5.2.11 is not the last version. I see that last version is 5.5.7 http://ftp.debian.org/debian/pool/main/w/whois/

Solution

Since your distribution use ubuntu xenial packages (Get:1 http://archive.ubuntu.com/ubuntu xenial/main), the result you see is coherent: https://packages.ubuntu.com/xenial/whois.

To use a more recent version, you can:

change the base distribution
try to build it from source
download the whois_5.5.7_amd64.deb file and install it with dpkg, but you risk to miss some dependencies.