Ubuntu – Configuring samba to provide subdomains on a local network

I need to setup an ubuntu VM as a local webserver. I want to use samba to provide some DNS support. The box is accessable from the browser using the NET-BIOS name 'my.box'.
However when I try a subdomain 'something.my.box' no ip is resolved.

I don't have a clue about windows networking. I used this sample smb.conf to configure samba on ubuntu 9.10:

    [global]
    ; General server settings
    netbios name = YOUR_HOSTNAME
    server string =
    workgroup = YOUR_WORKGROUP
    announce version = 5.0
    socket options = TCP_NODELAY IPTOS_LOWDELAY SO_KEEPALIVE SO_RCVBUF=8192 SO_SNDBUF=8192

    passdb backend = tdbsam
    security = user
    null passwords = true
    username map = /etc/samba/smbusers
    name resolve order = hosts wins bcast

    wins support = yes

    printing = CUPS
    printcap name = CUPS

    syslog = 1
    syslog only = yes

; NOTE: If you need access to the user home directories uncomment the
; lines below and adjust the settings to your hearts content.
;[homes]
    ;valid users = %S
    ;create mode = 0600
    ;directory mode = 0755
    ;browseable = no
    ;read only = no
    ;veto files = /*.{*}/.*/mail/bin/

; NOTE: Only needed if you run samba as a primary domain controller.
; Not needed as this config doesn't cover that matter.
;[netlogon]
    ;path = /var/lib/samba/netlogon
    ;admin users = Administrator
    ;valid users = %U
    ;read only = no

; NOTE: Again - only needed if you're running a primary domain controller.
;[Profiles]
    ;path = /var/lib/samba/profiles
    ;valid users = %U
    ;create mode = 0600
    ;directory mode = 0700
    ;writeable = yes
    ;browseable = no

; NOTE: Inside this place you may build a printer driver repository for
; Windows - I'll cover this topic in another HOWTO.
[print$]
    path = /var/lib/samba/printers
    browseable = yes
    guest ok = yes
    read only = yes
    write list = root
    create mask = 0664
    directory mask = 0775

[printers]
    path = /tmp
    printable = yes
    guest ok = yes
    browseable = no

; Uncomment if you need to share your CD-/DVD-ROM Drive
;[DVD-ROM Drive]
    ;path = /media/cdrom
    ;browseable = yes
    ;read only = yes
    ;guest ok = yes

[MyFiles]
    path = /media/samba/
    browseable = yes
    read only = no
    guest ok = no
    create mask = 0644
    directory mask = 0755
    force user = YOUR_USERNAME
    force group = YOUR_USERGROUP