Staff Software Engineer - Active Directory Internals & Directory Services

Cohesity is the leader in AI-powered data security. Over 13,600 enterprise customers, including over 85 of the Fortune 100 and nearly 70% of the Global 500, rely on Cohesity to strengthen their resilience while providing Gen AI insights into their vast amounts of data. Formed from the combination of Cohesity with Veritas’ enterprise data protection business, the company’s solutions secure and protect data on-premises, in the cloud, and at the edge. Backed by NVIDIA, IBM, HPE, Cisco, AWS, Google Cloud, and others, Cohesity is headquartered in Santa Clara, CA, with offices around the globe.  

We’ve been named a Leader by multiple analyst firms and have been globally recognized for Innovation, Product Strength, and Simplicity in Design , and our culture. 

Want to join the leader in AI-powered data security? 

About the Role

We're looking for an engineer who understands Active Directory the way its designers do — not just how to administer it, but how it actually works underneath: how objects replicate, how changes are tracked, how deletions age out, and how identity continuity is preserved across restores. You'll build and harden the core engine that reads, tracks, and safely writes AD state, powering reliable backup, synchronization, and recovery at scale.

This is a deep-systems role. If you've ever debugged a replication metadata mismatch, reasoned about USN rollback, or cared about SID history surviving a cross-domain restore, you'll be at home here.

What You'll Do

• Design and implement the directory engine that discovers, tracks, and safely applies changes to Active Directory objects.
• Build robust change-tracking pipelines using DirSync, USN cookies, and change notification, handling cursor persistence, catch-up, and re-sync correctly.
• Implement correct object lifecycle handling — tombstones, deleted-object lifetime, and Recycle Bin semantics — for accurate backup and recovery.
• Guarantee identity continuity across operations: SID, SID history, and GUID preservation and validation.
• Implement safe write paths — modify, ModifyDN, and object creation — with idempotency, conflict handling, and integrity guarantees.
• Work with AD-integrated DNS and Group Policy internals to ensure complete, consistent capture and restore.
• Diagnose and resolve complex replication, consistency, and LDAP edge cases in production environments.

Required Skills & Experience

You should have hands-on, internals-level expertise across most of the following:

Schema & Replication

• AD schema, object classes, and linked-value replication
• Replication metadata, USN semantics, and consistency reasoning

Directory Access

• LDAP search and controls, including paged and persistent search
• DirSync, USN cookies, and change notification for change tracking

Object Lifecycle

• Tombstones, deleted-object lifetime, and AD Recycle Bin behavior

Identity Continuity

• SID, SID history, and GUID continuity semantics across domains and restores

Group Policy & DNS

• Group Policy internals: GPC / GPT and SYSVOL
• AD-integrated DNS zones and records

Safe Writes

• Correct and safe modify, ModifyDN, and object-create operations

Nice to Have

• Experience building backup, replication, disaster-recovery, or migration tooling for Active Directory.
• Familiarity with Entra ID / Azure AD hybrid environments.
• Depth in C/C++, C#, Go; systems-level performance work.
• Experience operating against large, multi-domain / multi-forest deployments.

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Equal Employment Opportunity Employer (EEOE)

Cohesity is an Equal Employment Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, creed, religion, sex, sexual orientation, national origin or nationality, ancestry, age, disability, gender identity or expression, marital status, veteran status or any other category protected by law.

If you are an individual with a disability and require a reasonable accommodation to complete any part of the application process, or are limited in the ability or unable to access or use this online application process and need an alternative method for applying, you may contact us at 1-855-9COHESITY or [email protected] for assistance.

In-Office Expectations

Cohesity employees who are within a reasonable commute (e.g. within a forty-five (45) minute average travel time) work out of our core offices 2-3 days a week of their choosing.

We strongly prefer candidates who are currently located in or near the designated job location. Candidates outside the area should apply only if they are committed to relocating prior to their start date and have the legal right to work in the job location.