dnssec-verify: 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-verify - from package: bind9utils

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

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