Any DNS gurus

[Gidan]

I had an issue with a zone file last night and am need another opionion or 2

Are zone files read linearly?

In the zone file I had

domain.com. 14400 IN MX 10 mail2.domain.com.
mail2 14400 IN A A.B.C.D

I would get a dig responce of
domain.com. 14400 IN MX 10 B.C.D.domain.com
It wouldn't work, however when I did

mail2 14400 IN A A.B.C.D
domain.com. 14400 IN MX 10 mail2.domain.com.

It would work just fine
domain.com. 14400 IN MX 10 mail2.domain.com


Anyone out there that can explain this? I didn't think that zone files were handled linearly but I guess it possible.