Chapter 3 - section 3.4 - Given a scenario, implement IPv4 and IPv6 network services

section 3.4

Objective – Dynamic Addressing, Name Resolution, and Time Protocols

• Dynamic addressing
▸ DHCP
▸ Reservations
▸ Scope
▸ Lease time
▸ Options
▸ Relay / IP helper
▸ Exclusions
▸ Stateless address autoconfiguration (SLAAC)
• Name resolution
▸ DNS
▸ Domain Name Security Extensions (DNSSEC)
▸ DNS over HTTPS (DoH)
▸ DNS over TLS (DoT)
▸ Record types
▸ Address (A)
▸ AAAA
▸ Canonical name (CNAME)
▸ Mail exchange (MX)
▸ Text (TXT)
▸ Nameserver (NS)
▸ Pointer (PTR)
▸ Zone types
▸ Forward
▸ Reverse
▸ Authoritative vs. non-authoritative
▸ Primary vs. secondary
▸ Recursive
▸ Hosts file
• Time protocols
▸ NTP
▸ Precision Time Protocol (PTP)
▸ Network Time Security (NTS)

Dynamic Addressing – DHCP

• Automatically assigns IP configuration
• Provides IP address, subnet mask, gateway, DNS
• Uses UDP ports 67 (server) and 68 (client)
• Reduces manual configuration (exam critical)

DHCP – Reservations

• Assigns same IP to a specific MAC address
• Managed centrally on DHCP server
• Common for servers and printers
• Still uses DHCP process

DHCP – Scope

• Range of IP addresses DHCP can assign
• Defined per subnet
• Includes options and exclusions
• Misconfigured scope causes IP issues

DHCP – Lease Time

• Duration an IP address is assigned
• Can be short or long based on network needs
• Clients must renew lease periodically
• Short leases increase DHCP traffic

DHCP – Options

• Additional configuration parameters
• Examples: default gateway, DNS servers, NTP
• Applied per scope or reservation
• Exam frequently tests option purpose

DHCP – Relay / IP Helper

• Forwards DHCP requests across subnets
• Required because DHCP is broadcast-based
• Common on routers and Layer 3 switches
• Exam term: IP helper address

DHCP – Exclusions

• IP addresses DHCP will not assign
• Prevents conflicts with statically assigned IPs
• Defined within a scope
• Common for network devices

Dynamic Addressing – SLAAC

• Stateless Address Autoconfiguration
• Used by IPv6
• No DHCP server required
• Router advertisements provide prefix
• Often combined with DHCPv6

Name Resolution – DNS

• Resolves hostnames to IP addresses
• Uses UDP/TCP port 53
• Critical for network functionality
• Hierarchical and distributed system

DNS Security – DNSSEC

• Protects against DNS spoofing and poisoning
• Uses digital signatures
• Ensures authenticity and integrity
• Does NOT encrypt traffic

DNS Security – DoH and DoT

• Encrypt DNS queries
• DoH uses HTTPS (TCP 443)
• DoT uses TLS (TCP 853)
• Improves privacy and security

DNS Record – Address (A)

• Maps hostname to IPv4 address
• Most common DNS record
• Exam basic requirement

DNS Record – AAAA

• Maps hostname to IPv6 address
• IPv6 equivalent of A record
• Common exam comparison question

DNS Record – Canonical Name (CNAME)

• Alias pointing to another hostname
• Cannot coexist with other records
• Simplifies name management

DNS Record – Mail Exchange (MX)

• Identifies mail servers for a domain
• Uses priority values
• Lower number = higher priority

DNS Record – Text (TXT)

• Stores arbitrary text data
• Used for SPF, DKIM, domain verification
• Common in email security

DNS Record – Nameserver (NS)

• Identifies authoritative DNS servers
• Delegates DNS authority
• Critical for zone functionality

DNS Record – Pointer (PTR)

• Used for reverse DNS lookups
• Maps IP address to hostname
• Stored in reverse lookup zones

DNS Zone – Forward

• Resolves hostname to IP address
• Most commonly used zone type
• Uses A and AAAA records

DNS Zone – Reverse

• Resolves IP address to hostname
• Uses PTR records
• Important for logging and email validation

DNS – Authoritative vs. Non-authoritative

• Authoritative: provides original answers
• Non-authoritative: cached responses
• Exam tests authority concept

DNS – Primary vs. Secondary

• Primary: read/write zone
• Secondary: read-only copy
• Used for redundancy and load sharing

DNS – Recursive

• Performs full query resolution
• Contacts multiple DNS servers
• Used by client-facing resolvers

Name Resolution – Hosts File

• Local static name resolution
• Checked before DNS
• Used for testing and overrides
• Manual management required

Time Protocol – NTP

• Network Time Protocol
• Synchronizes system clocks
• Uses UDP port 123
• Critical for logs and authentication

Time Protocol – Precision Time Protocol (PTP)

• Higher accuracy than NTP
• Used in financial and industrial networks
• Requires hardware support
• IEEE 1588 standard

Time Protocol – Network Time Security (NTS)

• Secures NTP communications
• Uses TLS for authentication
• Prevents time spoofing attacks
• Newer exam topic

N10-009 Sample Questions – Addressing & DNS

• Q: Which protocol automatically assigns IP configuration?
▸ A: DHCP
• Q: Which DNS record maps a hostname to IPv6?
▸ A: AAAA
• Q: Which protocol secures DNS queries over HTTPS?
▸ A: DoH
• Q: Which protocol synchronizes network time?
▸ A: NTP