nnsd: 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 CentOS possible default full paths are:

/usr/bin/nnsd - from package: tcllib

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/nnsd - from package: tcllib

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

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