I have two DNS zone files can anyone please tell me in which one I have to add an SPF record?

Zone (localhost.zone):

$TTL    86400
@               IN SOA  @       root (
                                        42              ; serial (d. adams)
                                        3H              ; refresh
                                        15M             ; retry
                                        1W              ; expiry
                                        1D )            ; minimum

                IN NS           @
                IN A            127.0.0.1
                IN AAAA         ::1

Zone (localdomain.zone):

$TTL    86400
@               IN SOA  localhost root (
                                        42              ; serial (d. adams)
                                        3H              ; refresh
                                        15M             ; retry
                                        1W              ; expiry
                                        1D )            ; minimum
                IN NS           localhost
localhost       IN A            127.0.0.1

Solution 1:

The short answer is none of the above. Those are standard zones commonly added to DNS servers so they will resolve the name localhost and localhost.localdomain. These entries are added so the DNS server does not forward requests for localhost to your ISP, or other public DNS servers. The localhost zone is required by RFC1919

RFC1919 

4.1 Boot file setup

   Certain zones should always be present in nameserver configurations:

           primary         localhost               localhost
           primary         0.0.127.in-addr.arpa    127.0
           primary         255.in-addr.arpa        255
           primary         0.in-addr.arpa          0

If you have no other zones configured, then you are probably looking at the wrong DNS server.

Try running the command dig @8.8.8.8 -t ns example.org. Replace the example.org with your actual domain name that you are trying to send email from. This will give you the list of name servers authorative for your zone from Google's perspective.

my domain name is vns6.wtech.in

Is that your hostname or domain name? Do you own wtech.in? If you do, then it sure appears like your DNS is being handled by the servers named orderbox-dns.com.? I am not entirely sure who they are, but I would guess they belong to the DNS regiatrar you got the domain from. There is probably a web interface somewhere that allows you to modify the records within their system.

$ dig @8.8.8.8 -t ns wtech.in

; <<>> DiG 9.7.3 <<>> @8.8.8.8 -t ns wtech.in
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23606
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;wtech.in.                      IN      NS

;; ANSWER SECTION:
wtech.in.               37904   IN      NS      enow.earth.orderbox-dns.com.
wtech.in.               37904   IN      NS      enow.mars.orderbox-dns.com.
wtech.in.               37904   IN      NS      enow.mercury.orderbox-dns.com.
wtech.in.               37904   IN      NS      enow.venus.orderbox-dns.com.

;; Query time: 22 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Wed Feb 29 00:43:53 2012
;; MSG SIZE  rcvd: 143