[CentOS] About DNS service

I've followed these commands successfully :

- yum install bind bind-chroot bind-libs bind-utils

- service named start

When I used " host x.domain.com localhost"

I got :

using domain name server :
name : localhost
address : 172.0.0.1#53

host x.domain.com not found: 2(SERVFAIL)

I've changed the ip settings from (Automatic dhcp to manual ) but with the
same result...

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