[Samba] access to share with dns alias hostname

[banda bassotti]

Hello, I'v to migrate one file server (old samba 3) to a new file samba 4,
I thought I could use the parameters netbios aliases = oldsamba but it
doesn't work, trying to access the share, with the old names, the
credentials popup appears and the log show:

  gss_accept_sec_context failed with [ Miscellaneous failure (see text):
Failed to find cifs/oldsamba3 at lan.corp(kvno 107) in keytab
MEMORY:cifs_srv_keytab (arcfour-hmac-md5)]

unfortunately I have to keep active also the old server for which I thought
I could solve with the dns.

any help?

thnx.