dnswalk: 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/bin/dnswalk - from package: dnswalk

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

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