Cloud & Infrastructure Topics
Cloud platform services, infrastructure architecture, Infrastructure as Code, environment provisioning, and infrastructure operations. Covers cloud service selection, infrastructure provisioning patterns, container orchestration (Kubernetes), multi-cloud and hybrid architectures, infrastructure cost optimization, and cloud platform operations. For CI/CD pipeline and deployment automation, see DevOps & Release Engineering. For cloud security implementation, see Security Engineering & Operations. For data infrastructure design, see Data Engineering & Analytics Infrastructure.
Active Directory Architecture and Management
Designing, operating and recovering Active Directory Domain Services and the directory estate around it. Covers logical and physical structure (forests, trees, domains, OUs, trusts, schema extension, FSMO roles, Global Catalog, RODCs), sites and replication topology, domain controller placement, promotion, upgrade and functional levels, DC locator and AD-integrated DNS, domain join, Kerberos and NTLM authentication including SPNs and delegation, token size and SID history, LDAP binds and query tuning, Group Policy design, processing order, filtering, deployment and troubleshooting, user, group, computer and service account management including PowerShell account scripting and account lockout investigation, delegation of control and tiered administration, fine-grained password policy, backup, authoritative restore, forest recovery and USN rollback, AD hardening against Kerberoasting, DCSync and Golden Ticket attacks, forest migration, and hybrid identity with Microsoft Entra ID (Microsoft Entra Connect, Cloud Sync, password hash sync, pass-through authentication, federation, password writeback). Questions are asked from the directory administrator's and architect's seat. Platform-neutral identity protocols and lifecycle design, Windows file-server administration (shares, NTFS permissions, profiles), Linux directory integration, and generic DNS and DHCP service operations are covered elsewhere.
Networking Fundamentals and Protocols
The core model of how networks move data: the OSI and TCP/IP layers, the Internet Protocol suite, transport protocols (TCP versus UDP), encapsulation, and TCP behavior including congestion control. Covers the protocol foundations every networking and infrastructure discussion builds on, from link layer through transport. The conceptual bedrock beneath addressing, routing, and switching.
IP Addressing and Subnetting
Working with IP address space: IPv4 and IPv6 addressing, subnet masks and CIDR notation (including why classful addressing was abandoned), VLSM calculation, route summarization from an addressing standpoint, private (RFC1918), ULA, link-local (including 169.254 self-assigned) and public ranges, and multicast address ranges. Covers designing hierarchical addressing schemes for sites, VLANs, security zones, DMZs and data centers, laying out prefixes so ACL and QoS policy stays compact, NAT and CGNAT for address conservation, static versus DHCP-assigned addressing, IPAM practice, renumbering after mergers or overlaps, and IPv4-to-IPv6 transition (dual-stack, tunneling, NAT64/DNS64). Boundary: routing protocol operation, cloud VPC topology, DNS and DHCP service operation, and firewall design are covered elsewhere.
DNS, DHCP, and Name Resolution
How names and addresses are served and kept working on a network. DNS: resolution flow (stub, recursive, authoritative, root/TLD referrals), host-side resolver configuration and why one machine or process resolves differently from another, record types and their pitfalls (including apex aliasing, MX, SRV and CAA use), zones, delegation and glue, caching, TTL and negative caching, split-horizon and private zones, reverse DNS, zone transfers (AXFR/IXFR, TSIG), DNSSEC and key rollover, resolver and authoritative fleet design, forwarding versus running recursion, encrypted DNS (DoH/DoT), truncation, TCP fallback and EDNS, DNS-layer attacks (cache poisoning, amplification, spoofed-source floods), DNS health from the user's point of view, and DNS changes, mail and registrar migrations and outages. DHCP: address assignment and leases, scopes and sizing, reservations, relay across VLANs including relay agent information (option 82), redundancy and failover, and rogue or exhausted-scope failures. Includes diagnosing resolution failures that masquerade as wider outages. Excludes the layered network fault-isolation method and general packet capture, Active Directory-integrated DNS on domain controllers, DNS-based service registries for microservices, load-balancing algorithm design and global traffic steering, incident-command process and SLO or error-budget design, and generic scripting or infrastructure-as-code tooling.
AWS Core Services and Architecture
Amazon Web Services' core service catalog and how the pieces compose into a working system: EC2, Lambda, S3, VPC, IAM, RDS, and the managed-service ecosystem. Covers service selection within AWS, common reference architectures, the AWS Well-Architected Framework pillars, and operational patterns specific to the platform. For provider-agnostic compute or storage trade-offs, see the cross-cloud entries.
Linux System Administration
Operating and maintaining Linux and Unix systems: filesystems and permissions, process and service management, package management and updates, shell and scripting, storage, and network configuration on the host. Covers day-to-day administration, troubleshooting, monitoring and tuning host resource usage (CPU, memory, swap, and I/O), and hardening of Linux servers that underpin most infrastructure. The Linux operator's core skill set.
Network Troubleshooting and Diagnostics
Systematically diagnosing network problems: a layered troubleshooting methodology, diagnostic tools and commands (ping, traceroute, tcpdump, packet capture), root-cause analysis, and connectivity and user-access issues. Covers isolating faults across the stack, reading packet-level evidence, and driving from symptom to root cause. The diagnostic discipline that spans all networking layers.
Virtualization and Hypervisor Management
Running workloads on virtualized infrastructure: hypervisors (type 1 and type 2), virtual machine lifecycle and management, resource allocation and overcommit, and the trade-offs between virtualization and containerization. Covers provisioning and operating VMs, capacity on virtual hosts, and how virtualization underlies both on-premises and cloud infrastructure.