dnsip: 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/dnsip - from package: ndjbdns

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

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