Actually looking closer... I'm not sure how that is working at all. BIND must be seeing your configuration and transparently fixing this for you. Here is what your configuration should probably look like
Now there are still a few things that could be wrong with the above. In the example you are posting you keep on showing a ns1 and a ns2... but you have them as the same address. This is absolutely pointless. If there really is 2 name servers then add back in that entry.
@ IN SOA ns1.example.cl. hostmaster.example.cl. (
1 ; serial
86400 ; refresh
7200 ; retry
1209600 ; expiry
10800 ) ; minimum
example.cl. IN NS ns1.example.cl.
example.cl. IN MX 0 correo.example.cl.
example.cl. IN A 200.42.X.Y
www IN A 200.42.X.Y
ns1 IN A 200.42.X.Y
correo IN A 200.42.X.Y
In your original file you have the master name server set as the domain name, this is wrong and is corrected above. You also have ns1 and ns2 setup as your MX records, again if these are separate servers, and actually are Mail servers (that forward to correo?) then this may be correct, but in the example above I assumed that you want mail delivered directly to correo.
Your original file was also missing a "." at the end of all the "example.cl" which would make BIND expand it to "example.cl.example.cl."
You also had a localhost.example.cl A record in there pointing to 127.0.0.1.... this is absolutely bogus data and will be rejected by any properly configured DNS client.
To add the correo.example.cl record see above. Since you seem to be pointing everything to the same, singular, public IP address I put the same address for it as well.
Remember that your PTR records will also need to be set to show the PTR record for 200.42.X.Y (or whatever the address for correo.example.cl is) pointing to correo.example.cl. This will probably need to be done by your ISP as they are most likely the ones who control the PTR record for your address space.
Also in the future rather then posting a screenshot please use the [ code] [ /code] tags (without the spaces), or click the # symbol at the top after selecting a block of text.