California Civil Code 1954(d)(3) The Landlords Right of Entry Notice may be reasonably given 1.) In Writing Using the State's Notice of Intent to Enter Dwelling...may be handed personally to the tenant or agent for tenant; sent by regular U.S.mail, optional carrier, by service upon tenant 2.) Oral Notice as long as tenant has requested service or repair. 3) Verifiable Electronic Notice; e-mail, or other form of personal electronic devise. All notices must include reason for entry, date and time of entry.( generally regular business hours 8:00am - 6:00pm)
So I read where no POSTING to physical front door is necessary.
It further suggest that if the Tenant becomes difficult by not confirming the Landlord Right of Entry; the Landlord may override the tenants opposition to entry, by having a witness oversee the Landlords Entry. A Witness may be a law enforcement officer, agent or unbiased individual. A tenant may not restrict the property owner or landlord the right to maintain the property. The tenants constant refusal will constitute a Nuisance of Permitting Waste upon the Property which becomes a just cause for eviction.
Reference; The California Landlord's Law Book: Rights and Responsibilities; Nolo Press