CompTIA Network+ flashcards
CompTIA Network+ · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- OSI Layer 3
- Network layer; routes packets between networks using logical IP addresses. Routers operate here, and IP, ICMP, and routing protocols function at this layer.
- TCP three-way handshake
- Connection setup sequence: client sends SYN, server replies SYN-ACK, client sends ACK. It synchronizes sequence numbers before data transfer begins.
- APIPA address range
- 169.254.0.0/16; a host self-assigns this link-local address when DHCP is unavailable. It cannot route beyond the local subnet.
- Private IPv4 ranges
- 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are non-routable on the internet and require NAT for external communication.
- DNS MX record
- Mail exchanger record; identifies the mail server responsible for accepting email for a domain, with a preference value for prioritization.
- IPv6 link-local prefix
- fe80::/10; automatically configured on every IPv6 interface for communication on the local link only and never forwarded by routers.
- Usable hosts formula
- For a subnet with h host bits, usable host addresses equal 2^h minus 2, subtracting the network and broadcast addresses.
- Cat6a maximum distance
- Cat6a supports 10 Gbps Ethernet up to 100 meters on copper cabling and has stricter shielding to reduce crosstalk than Cat6.
- DHCP DORA process
- Discover, Offer, Request, Acknowledge. Client broadcasts Discover, server Offers an address, client Requests it, server Acknowledges the lease.
- 802.1Q VLAN tag
- A 4-byte tag inserted into Ethernet frames that carries a 12-bit VLAN ID, allowing trunk links to carry multiple VLANs.
- STP purpose
- Spanning Tree Protocol blocks redundant switch paths to prevent Layer 2 loops and broadcast storms while maintaining a loop-free topology.
- Wi-Fi 6 standard
- IEEE 802.11ax; operates in 2.4 GHz and 5 GHz bands, improves efficiency in dense environments using OFDMA and MU-MIMO.
- NAT overload
- Also called PAT; maps many private IP addresses to one public IP address using different source port numbers.
- SD-WAN characteristic
- Software-defined WAN centrally manages and prioritizes traffic across multiple WAN links such as broadband, MPLS, and cellular.
- SNMP traps
- Unsolicited notifications sent by an SNMP agent to a manager on UDP port 162 when a defined event occurs.
- RTO vs RPO
- Recovery time objective is maximum acceptable downtime; recovery point objective is maximum acceptable data loss measured in time.
- 3-2-1 backup rule
- Keep three copies of data, on two different media types, with one copy stored offsite or offline.
- Syslog default port
- UDP 514; syslog messages carry severity levels from 0 emergency through 7 debug for centralized logging.
- Full backup
- Copies all selected data every time, allowing simplest restoration but requiring the most storage and backup time.
- Incremental backup
- Copies only data changed since the last backup of any type; restoration requires the last full backup plus every incremental since.
- CIA triad
- Confidentiality protects data from unauthorized disclosure, integrity prevents unauthorized modification, and availability ensures timely access to resources.
- RADIUS port numbers
- UDP 1812 for authentication and authorization, UDP 1813 for accounting; commonly used for centralized AAA for network access.
- TACACS+ protocol
- Cisco-developed AAA protocol that uses TCP port 49 and separates authentication, authorization, and accounting functions.
- Stateful firewall
- Tracks active connections in a state table and permits return traffic that matches an established session.
- IDS vs IPS
- An IDS detects and alerts on suspicious traffic; an IPS sits inline and can block or drop malicious traffic.
- IPsec ESP
- Encapsulating Security Payload provides confidentiality and integrity by encrypting packet payloads; AH provides integrity but no encryption.
- 802.1X
- Port-based network access control that authenticates devices through a supplicant, authenticator, and authentication server before allowing LAN access.
- APIPA indicates
- A 169.254.x.x address on a host usually means the DHCP server was unreachable or failed to respond.
- Traceroute purpose
- Maps the path packets take to a destination and shows per-hop latency, helping locate routing loops or failed links.
- DNS troubleshooting command
- nslookup or dig queries DNS servers directly to verify name resolution and record values independent of local browser cache.
- Duplex mismatch symptom
- Late collisions and poor throughput occur when one side is full duplex and the other half duplex on the same link.
- Jitter
- Variation in packet delay over time; high jitter degrades real-time voice and video even when average latency is acceptable.