Defense in Depth
Hosted by David Spark & Steve Zalewski & Geoff Belknap & Edward Contreras
One contested security question per week, argued by a CISO co-host and a guest in about 30 minutes.
- Level
- Practitioner, assumes you work in or study security
- Status
- Active, last episode
- Who's behind it
- Media outlet, CISO Series sourceFeed copyright: Spark Media Solutions, LLC. Sponsored guests are labeled in show notes.
- Last verified
Listed underCISO and leadership
Editorial take
CISO Series' single-topic show, and the better pick if you want depth over pace. Each episode takes one debate from a LinkedIn or Reddit post, such as whether to phish your own employees or how to measure a CISO, and works through it with a co-host CISO (most often Steve Zalewski, formerly CISO of Levi Strauss, or Edward Contreras of Frost Bank) and one guest. At about 30 minutes it is a commute-sized episode that stays on one problem. Expect opinions from senior practitioners rather than evidence or data. About one in four 2026 episodes has a sponsored vendor guest, and a run of episodes on the vendor pitch and buying process will matter more to people who sell security than to defenders.
Last hand-checked 2026-09-30.
Listen if you …
- want one security leadership question argued properly in 30 minutes
- are moving into management and want to hear how CISOs reason through trade-offs
- like the CISO Series format but find the main show too quick
Skip if you …
- you want research or data, this is experienced opinion
- vendor sales topics bore you, a steady share of episodes are about buying and selling security
Start with these 3 episodes
- 01
Should You Phish Your Employees or Not?
· 27 min · Beginner
A debate every security team has: whether phishing tests build defenses or just break trust.
- 02
How Should We Measure the Performance of a CISO?
· 29 min · Practitioner
Representative of the format: one hard leadership question, worked through by two CISOs.
- 03
Identity and Access Management (IAM) in an Agentic AI World
· 30 min · Practitioner
A timely identity episode: what IAM has to change when AI agents act on users' behalf.
About the show
Defense in Depth is produced by CISO Series and hosted by David Spark with a rotating co-host CISO, most often Steve Zalewski, Geoff Belknap or Edward Contreras. Each weekly episode takes one controversial discussion from the security community and debates it with a guest.
The show launched in January 2019 and has published over 370 episodes, most around 25 to 35 minutes. The feed also carries occasional bonus episodes of Super Cyber Friday Express, a 20 minute cut of CISO Series' live Friday show.
Notable guests
- Yaron Levi
- Will Gregorian
- Mark Eggleston
- Abby Kearns
- Tomás Maldonado
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