Networking Fundamentals - 24%

• Layer 1 – Physical
• Layer 2 – Data link
• Layer 3 – Network
• Layer 4 – Transport
• Layer 5 – Session
• Layer 6 – Presentation
• Layer 7 – Application

- Data encapsulation and decapsulation within the OSI model context

• Ethernet header
• Internet Protocol (IP) header
• Transmission Control Protocol (TCP)/User Datagram Protocol (UDP) headers
• TCP flags
• Payload
• Maximum transmission unit (MTU)

• Peer-to-peer
• Client-server
• Local area network (LAN)
• Metropolitan area network (MAN)
• Wide area network (WAN)
• Wireless local area network (WLAN)
• Personal area network (PAN)
• Campus area network (CAN)
• Storage area network (SAN)
• Software-defined wide area network (SDWAN)
• Multiprotocol label switching (MPLS)
• Multipoint generic routing encapsulation (mGRE)

- Service-related entry point

• Demarcation point
• Smartjack

- Virtual network concepts

• vSwitch
• Virtual network interface card (vNIC)
• Network function virtualization (NFV)
• Hypervisor

- Provider links

• Satellite
• Digital subscriber line (DSL)
• Cable
• Leased line
• Metro-optical

• Twisted pair
  1. Cat 5
  2. Cat 5e
  3. Cat 6
  4. Cat 6a
  5. Cat 7
  6. Cat 8
• Coaxial/RG-6
• Twinaxial
• Termination standards
  1. TIA/EIA-568A
  2. TIA/EIA-568B

- Fiber

• Single-mode
• Multimode

- Connector types

• Local connector (LC), straight tip (ST), subscriber connector (SC), mechanical transfer (MT), registered jack (RJ)
  1. Angled physical contact (APC)
  2. Ultra-physical contact (UPC)
• RJ11
• RJ45
• F-type connector
• Transceivers/media converters
• Transceiver type
  1. Small form-factor pluggable (SFP)
  2. Enhanced form-factor pluggable (SFP+)
  3. Quad small form-factor pluggable (QSFP)
  4. Enhanced quad small form-factor pluggable (QSFP+)

- Cable management

• Patch panel/patch bay
• Fiber distribution panel
• Punchdown block
  1. 66
  2. 110
  3. Krone
  4. Bix

- Ethernet standards

• Copper
  1. 10BASE-T
  2. 100BASE-TX
  3. 1000BASE-T
  4. 10GBASE-T
  5. 40GBASE-T
• Fiber
  1. 100BASE-FX
  2 .100BASE-SX
  3. 1000BASE-SX
  4. 1000BASE-LX
  5. 10GBASE-SR
  6. 10GBASE-LR
  7. Coarse wavelength division multiplexing (CWDM)
  8. Dense wavelength division multiplexing (DWDM)
  9. Bidirectional wavelength division multiplexing (WDM)

• RFC1918
• Network address translation (NAT)
• Port address translation (PAT)

- IPv4 vs. IPv6

• Automatic Private IP Addressing (APIPA)
• Extended unique identifier (EUI-64)
• Multicast
• Unicast
• Anycast
• Broadcast
• Link local
• Loopback
• Default gateway

- IPv4 subnetting

• Classless (variable-length subnet mask)
• Classful
  1. A
  2. B
  3. C
  4. D
  5. E
• Classless Inter-Domain Routing (CIDR) notation

- IPv6 concepts

• Tunneling
• Dual stack
• Shorthand notation
• Router advertisement
• Stateless address autoconfiguration (SLAAC)

- Virtual IP (VIP)
- Subinterfaces

• File Transfer Protocol (FTP) 20/21
• Secure Shell (SSH) 22
• Secure File Transfer Protocol (SFTP) 22
• Telnet 23
• Simple Mail Transfer Protocol (SMTP) 25
• Domain Name System (DNS) 53
• Dynamic Host Configuration Protocol (DHCP) 67/68
• Trivial File Transfer Protocol (TFTP) 69
• Hypertext Transfer Protocol (HTTP) 80
• Post Office Protocol v3 (POP3) 110
• Network Time Protocol (NTP) 123
• Internet Message Access Protocol (IMAP) 143
• Simple Network Management Protocol (SNMP) 161/162
• Lightweight Directory Access Protocol (LDAP) 389
• Hypertext Transfer Protocol Secure (HTTPS) [Secure Sockets Layer (SSL)] 443
• HTTPS [Transport Layer Security (TLS)] 443
• Server Message Block (SMB) 445
• Syslog 514
• SMTP TLS 587
• Lightweight Directory Access Protocol (over SSL) (LDAPS) 636
• IMAP over SSL 993
• POP3 over SSL 995
• Structured Query Language (SQL) Server 1433
• SQLnet 1521
• MySQL 3306
• Remote Desktop Protocol (RDP) 3389
• Session Initiation Protocol (SIP) 5060/5061
• IP protocol types
  1. Internet Control Message Protocol (ICMP)
  2. TCP
  3. UDP
  4. Generic Routing Encapsulation (GRE)
  5. Internet Protocol Security (IPSec)
  - Authentication Header (AH)/Encapsulating Security Payload (ESP)

- Connectionless vs. connection-oriented

• Scope
• Exclusion ranges
• Reservation
• Dynamic assignment
• Static assignment
• Lease time
• Scope options
• Available leases
• DHCP relay
• IP helper/UDP forwarding

- DNS

• Record types
  1. Address (A vs. AAAA)
  2. Canonical name (CNAME)
  3. Mail exchange (MX)
  4. Start of authority (SOA)
  5. Pointer (PTR)
  6. Text (TXT)
  7. Service (SRV)
  8. Name server (NS)
• Global hierarchy
  1. Root DNS servers
• Internal vs. external
• Zone transfers
• Authoritative name servers
• Time to live (TTL)
• DNS caching
• Reverse DNS/reverse lookup/forward lookup
• Recursive lookup/iterative lookup

- NTP

• Stratum
• Clients
• Servers

• Core
• Distribution/aggregation layer
• Access/edge

- Software-defined networking

• Application layer
• Control layer
• Infrastructure layer
• Management plane

- Spine and leaf

• Software-defined network
• Top-of-rack switching
• Backbone

- Traffic flows

• North-South
• East-West

- Branch office vs. on-premises datacenter vs. colocation
- Storage area networks

• Connection types
  1. Fibre Channel over Ethernet (FCoE)
  2. Fibre Channel
  3. Internet Small Computer Systems Interface (iSCSI)

• Public
• Private
• Hybrid
• Community

- Service models

• Software as a service (SaaS)
• Infrastructure as a service (IaaS)
• Platform as a service (PaaS)
• Desktop as a service (DaaS)

- Infrastructure as code

• Automation/orchestration

- Connectivity options

• Virtual private network (VPN)
• Private-direct connection to cloud provider

- Multitenancy
- Elasticity
- Scalability
- Security implications

Network Implementations - 19%

• Layer 2 switch
• Layer 3 capable switch
• Router
• Hub
• Access point
• Bridge
• Wireless LAN controller
• Load balancer
• Proxy server
• Cable modem
• DSL modem
• Repeater
• Voice gateway
• Media converter
• Intrusion prevention system (IPS)/intrusion detection system (IDS) device
• Firewall
• VPN headend

- Networked devices

• Voice over Internet Protocol (VoIP) phone
• Printer
• Physical access control devices
• Cameras
• Heating, ventilation, and air conditioning (HVAC) sensors
• Internet of Things (IoT)
  1. Refrigerator
  2. Smart speakers
  3. Smart thermostats
  4. Smart doorbells
• Industrial control systems/supervisory control and data acquisition (SCADA)

• Dynamic routing
  1. Protocols [Routing Internet Protocol (RIP), Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP), Border Gateway Protocol (BGP)]
  2. Link state vs. distance vector vs. hybrid
• Static routing
• Default route
• Administrative distance
• Exterior vs. interior
• Time to live

- Bandwidth management

• Traffic shaping
• Quality of service (QoS)

• Port tagging/802.1Q
• Port aggregation
  1. Link Aggregation Control Protocol (LACP)
• Duplex
• Speed
• Flow control
• Port mirroring
• Port security
• Jumbo frames
• Auto-medium-dependent interface crossover (MDI-X)

- Media access control (MAC) address tables
- Power over Ethernet (PoE)/Power over Ethernet plus (PoE+)
- Spanning Tree Protocol
- Carrier-sense multiple access with collision detection (CSMA/CD)
- Address Resolution Protocol (ARP)
- Neighbor Discovery Protocol

• a
• b
• g
• n (WiFi 4)
• ac (WiFi 5)
• ax (WiFi 6)

- Frequencies and range

• 2.4GHz
• 5GHz

- Channels

• Regulatory impacts

- Channel bonding
- Service set identifier (SSID)

• Basic service set
• Extended service set
• Independent basic service set (Ad-hoc)
• Roaming

- Antenna types

• Omni
• Directional

- Encryption standards

• WiFi Protected Access (WPA)/WPA2 Personal [Advanced Encryption Standard (AES)/Temporal Key Integrity Protocol (TKIP)]
• WPA/WPA2 Enterprise (AES/TKIP)

- Cellular technologies

• Code-division multiple access (CDMA)
• Global System for Mobile Communications (GSM)
• Long-Term Evolution (LTE)
• 3G, 4G, 5G

- Multiple input, multiple output (MIMO) and multi-user MIMO (MU-MIMO)

Network Operations - 16%

• Device/chassis
  1. Temperature
  2. Central processing unit (CPU) usage
  3. Memory
• Network metrics
  1. Bandwidth
  2. Latency
  3. Jitter

- SNMP

• Traps
• Object identifiers (OIDs)
• Management information bases (MIBs)

- Network device logs

• Log reviews
  1. Traffic logs
  2. Audit logs
  3. Syslog
• Logging levels/severity levels

- Interface statistics/status

• Link state (up/down)
• Speed/duplex
• Send/receive traffic
• Cyclic redundancy checks (CRCs)
• Protocol packet and byte counts

- Interface errors or alerts

• CRC errors
• Giants
• Runts
• Encapsulation errors

- Environmental factors and sensors

• Temperature
• Humidity
• Electrical
• Flooding

- Baselines
- NetFlow data
- Uptime/downtime

• Change management
• Incident response plan
• Disaster recovery plan
• Business continuity plan
• System life cycle
• Standard operating procedures

- Hardening and security policies

• Password policy
• Acceptable use policy
• Bring your own device (BYOD) policy
• Remote access policy
• Onboarding and offboarding policy
• Security policy
• Data loss prevention

- Common documentation

• Physical network diagram
  1. Floor plan
  2. Rack diagram
  3. Intermediate distribution frame (IDF)/main distribution frame (MDF) documentation
• Logical network diagram
• Wiring diagram
• Site survey report
• Audit and assessment report
• Baseline configurations

- Common agreements

• Non-disclosure agreement (NDA)
• Service-level agreement (SLA)
• Memorandum of understanding (MOU)

• Switches
• Routers
• Firewalls

- Facilities and infrastructure support

• Uninterruptible power supply (UPS)
• Power distribution units (PDUs)
• Generator
• HVAC
• Fire suppression

- Redundancy and high availability (HA) concepts

• Cold site
• Warm site
• Hot site
• Cloud site
• Active-active vs. active-passive
  1. Multiple Internet service providers (ISPs)/diverse paths
  2. Virtual Router Redundancy Protocol (VRRP)/First Hop Redundancy Protocol (FHRP)
• Mean time to repair (MTTR)
• Mean time between failure (MTBF)
• Recovery time objective (RTO)
• Recovery point objective (RPO)

- Network device backup/restore

• State
• Configuration

Network Security - 19%

• Internal
• External

- Vulnerabilities

• Common vulnerabilities and exposures (CVE)
• Zero-day

- Exploits
- Least privilege
- Role-based access
- Zero Trust
- Defense in depth

• Network segmentation enforcement
• Screened subnet [previously known as demilitarized zone (DMZ)]
• Separation of duties
• Network access control
• Honeypot

- Authentication methods

• Multifactor
• Terminal Access Controller Access-Control System Plus (TACACS+)
• Single sign-on (SSO)
• Remote Authentication Dial-in User Service (RADIUS)
• LDAP
• Kerberos
• Local authentication
• 802.1X
• Extensible Authentication Protocol (EAP)

- Risk Management

• Security risk assessments
  1. Threat assessment
  2. Vulnerability assessment
  3. Penetration testing
  4. Posture assessment
• Business risk assessments
  1. Process assessment
  2. Vendor assessment

- Security information and event management (SIEM)

• Denial-of-service (DoS)/distributed denial-of-service (DDoS)
  1. Botnet/command and control
• On-path attack (previously known as man-in-the-middle attack)
• DNS poisoning
• VLAN hopping
• ARP spoofing
• Rogue DHCP
• Rogue access point (AP)
• Evil twin
• Ransomware
• Password attacks
  1. Brute-force
  2. Dictionary
• MAC spoofing
• IP spoofing
• Deauthentication
• Malware

- Human and environmental

• Social engineering
  1. Phishing
  2. Tailgating
  3. Piggybacking
  4. Shoulder surfing

• Secure SNMP
• Router Advertisement (RA) Guard
• Port security
• Dynamic ARP inspection
• Control plane policing
• Private VLANs
• Disable unneeded switchports
• Disable unneeded network services
• Change default passwords
• Password complexity/length
• Enable DHCP snooping
• Change default VLAN
• Patch and firmware management
• Access control list
• Role-based access
• Firewall rules
  1. Explicit deny
  2. Implicit deny

- Wireless security

• MAC filtering
• Antenna placement
• Power levels
• Wireless client isolation
• Guest network isolation
• Preshared keys (PSKs)
• EAP
• Geofencing
• Captive portal

- IoT access considerations

• Clientless VPN
• Split tunnel vs. full tunnel

- Remote desktop connection
- Remote desktop gateway
- SSH
- Virtual network computing (VNC)
- Virtual desktop
- Authentication and authorization considerations
- In-band vs. out-of-band management

• Camera
• Motion detection
• Asset tags
• Tamper detection

- Prevention methods

• Employee training
• Access control hardware
  1. Badge readers
  2. Biometrics
• Locking racks
• Locking cabinets
• Access control vestibule (previously known as a mantrap)
• Smart lockers

- Asset disposal

Network Troubleshooting - 22%

• Gather information
• Question users
• Identify symptoms
• Determine if anything has changed
• Duplicate the problem, if possible
• Approach multiple problems individually

- Establish a theory of probable cause

• Question the obvious
• Consider multiple approaches
  1. Top-to-bottom/bottom-to-top OSI model
  2. Divide and conquer

- Test the theory to determine the cause

• If the theory is confirmed, determine the next steps to resolve the problem
• If the theory is not confirmed, reestablish a new theory or escalate

- Establish a plan of action to resolve the problem and identify potential effects
- Implement the solution or escalate as necessary
- Verify full system functionality and, if applicable, implement preventive measures
- Document findings, actions, outcomes, and lessons learned

• Throughput
• Speed
• Distance

- Cable considerations

• Shielded and unshielded
• Plenum and riser-rated

- Cable application

• Rollover cable/console cable
• Crossover cable
• Power over Ethernet

- Common issues

• Attenuation
• Interference
• Decibel (dB) loss
• Incorrect pinout
• Bad ports
• Open/short
• Light-emitting diode (LED) status indicators
• Incorrect transceivers
• Duplexing issues
• Transmit and receive (TX/RX) reversed
• Dirty optical cables

- Common tools

• Cable crimper
• Punchdown tool
• Tone generator
• Loopback adapter
• Optical time-domain reflectometer (OTDR)
• Multimeter
• Cable tester
• Wire map
• Tap
• Fusion splicers
• Spectrum analyzers
• Snips/cutters
• Cable stripper
• Fiber light meter

• WiFi analyzer
• Protocol analyzer/packet capture
• Bandwidth speed tester
• Port scanner
• iperf
• NetFlow analyzers
• Trivial File Transfer Protocol (TFTP) server
• Terminal emulator
• IP scanner

- Command line tool

• ping
• ipconfig/ifconfig/ip
• nslookup/dig
• traceroute/tracert
• arp
• netstat
• hostname
• route
• telnet
• tcpdump
• nmap

- Basic network platform commands

• show interface
• show config
• show route

• Throughput
• Speed
• Distance
• Received signal strength indication (RSSI) signal strength
• Effective isotropic radiated power (EIRP)/power settings

- Considerations

• Antennas
  1. Placement
  2. Type
  3. Polarization
• Channel utilization
• AP association time
• Site survey

- Common issues

• Interference
  1. Channel overlap
• Antenna cable attenuation/signal loss
• RF attenuation/signal loss
• Wrong SSID
• Incorrect passphrase
• Encryption protocol mismatch
• Insufficient wireless coverage
• Captive portal issues
• Client disassociation issues

• Device configuration review
• Routing tables
• Interface status
• VLAN assignment
• Network performance baselines

- Common issues

• Collisions
• Broadcast storm
• Duplicate MAC address
• Duplicate IP address
• Multicast flooding
• Asymmetrical routing
• Switching loops
• Routing loops
• Rogue DHCP server
• DHCP scope exhaustion
• IP setting issues
• Missing route
• Low optical link budget
• Certificate issues
• Hardware failure
• Host-based/network-based firewall settings
• Blocked services, ports, or addresses
• Incorrect VLAN
• DNS issues
• NTP issues
• BYOD challenges
• Licensed feature issues
• Network performance issues