dnssec-coverage: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/sbin/dnssec-coverage - from package: bind9utils

You may install the required package with command apt-get install {package}

Error in other languages:
dnssec-coverage: bevel nie gevind nie
dnssec-coverage: comandă negăsită
dnssec-coverage: comando não encontrado
dnssec-coverage: commande introuvable
dnssec-coverage: command not found
dnssec-coverage: käsku ei ole
dnssec-coverage: không tìm thấy lệnh
dnssec-coverage: komanda nerasta
dnssec-coverage: Kommando nicht gefunden.
dnssec-coverage: kommandot finns inte
dnssec-coverage: komut yok
dnssec-coverage: nie znaleziono polecenia
dnssec-coverage: níor aimsíodh an t-ordú
dnssec-coverage: no se encontró la orden
dnssec-coverage: no s'ha trobat l'ordre
dnssec-coverage: opdracht niet gevonden
dnssec-coverage: parancs nem található
dnssec-coverage: perintah tidak ditemukan
dnssec-coverage: príkaz nenájdený
dnssec-coverage: příkaz nenalezen
dnssec-coverage: команда не найдена
dnssec-coverage: командата не е открита
dnssec-coverage: 命令找不到
dnssec-coverage: コマンドが見つかりません