California Code, Code of Civil Procedure - CCP § 1162

(1) By delivering a copy to the tenant personally.

(2) If he or she is absent from his or her place of residence, and from his or her usual place of business, by leaving a copy with some person of suitable age and discretion at either place, and sending a copy through the mail addressed to the tenant at his or her place of residence.

(3) If such place of residence and business cannot be ascertained, or a person of suitable age or discretion there can not be found, then by affixing a copy in a conspicuous place on the property, and also delivering a copy to a person there residing, if such person can be found; and also sending a copy through the mail addressed to the tenant at the place where the property is situated. Service upon a subtenant may be made in the same manner.

(1) By delivering a copy to the tenant personally.

(2) If he or she is absent from the commercial rental property, by leaving a copy with some person of suitable age and discretion at the property, and sending a copy through the mail addressed to the tenant at the address where the property is situated.

(3) If, at the time of attempted service, a person of suitable age or discretion is not found at the rental property through the exercise of reasonable diligence, then by affixing a copy in a conspicuous place on the property, and also sending a copy through the mail addressed to the tenant at the address where the property is situated. Service upon a subtenant may be made in the same manner.