The Zone window represents all the records in a zone, including the SOA record. The name of the zone appears in the Title bar. The various fields of the zone's SOA record appear in the upper area of the window.
Because the SOA record is seldom modified once created, the fields of the SOA record can be concealed by:
In Windows: Clicking on the three grey lines on the left of the window.
On the Mac: Clicking on the Disclosure triangle.