DNS check broking sometimes

[Ronan Lucio]

Hi All,

I have bind-8.2.3-REL installed in some clients.

Usually, if I run a host -a domain.com, it returns the informations
about such domain with mx record, soa, ns and etc.

Sometimes, after a few months, the client stating don´t receiving
mails properly and, when I run a host -a domain.com, it just
returns the ns informations and not more a soa and mx records.

Does anyone know what is wrong?

Thank´s to all

Ronan