Articles
DHCP scope, lease, reservation and relay
How a DHCP server is scoped to a subnet, how leases and reservations decide which address a client gets, and how a relay agent lets one server serve other segments.
Network services
Directly assigned
Articles
DNS and DHCP: names, addresses and automatic configuration
What DNS and DHCP each solve, how resolution and address assignment actually work, and why both are unauthenticated by default.
Articles
DNS records and resolution: which record answers a query, and where it comes from
How the common DNS record types answer different questions, how a resolver walks the delegations to the authoritative server that owns a name, and how a Cisco IOS-XE device resolves and serves names.
Articles
NTP and time synchronisation: keeping network clocks aligned
How NTP keeps network devices on the same clock - the server hierarchy, the round-trip measurement, and why unauthenticated time is a risk.