CNPLE flashcards
CNPLE · 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.
- Collapsed core
- A design that merges the core and distribution layers into one layer, typically used in smaller campuses to reduce cost and hops while keeping redundant paths.
- Spine-leaf topology
- A data center design where every leaf switch connects to every spine switch, giving uniform latency and predictable east-west traffic without spanning-tree dependence.
- Five nines availability
- An availability target of 99.999 percent uptime, which corresponds to roughly five minutes and fifteen seconds of downtime per year.
- Oversubscription ratio
- The ratio of total downstream capacity to uplink capacity at a layer, used to size aggregation and core links against expected traffic demand.
- OSPF adjacency requirements
- Neighbors must agree on area, hello and dead timers, authentication, stub flags, and MTU size before forming a full adjacency on a broadcast segment.
- BGP local preference
- An iBGP attribute propagated within an autonomous system; the highest value is preferred and it is evaluated before AS path length in best-path selection.
- STP root bridge election
- The switch with the lowest bridge ID wins, where bridge ID combines the configurable priority value and the switch MAC address.
- Native VLAN mismatch
- A condition where untagged frames on a trunk belong to different VLANs at each end, causing traffic leakage and CDP or logging warnings.
- EtherChannel requirements
- Bundled interfaces must share speed, duplex, trunk mode, and allowed VLANs; mismatches keep member ports from joining the channel.
- EIGRP feasible successor
- A backup route whose reported distance is lower than the feasible distance of the current successor, guaranteeing a loop-free alternate path.
- 802.1X authentication roles
- The supplicant is the endpoint, the authenticator is the switch port, and the authentication server is typically a RADIUS server validating credentials.
- IPsec ESP versus AH
- ESP encrypts and authenticates payloads, while AH provides integrity and origin authentication without confidentiality and cannot traverse NAT.
- DHCP snooping
- A switch feature that permits DHCP server replies only on trusted ports and builds a binding table of client MAC, IP, VLAN, and port.
- Dynamic ARP inspection
- A feature that validates ARP packets against the DHCP snooping binding table, dropping spoofed replies that attempt man-in-the-middle attacks.
- DMZ design
- A segmented zone holding public-facing services, separated from internal networks by firewalls so compromised hosts cannot directly reach internal assets.
- Syslog severity levels
- Numerical levels from 0 (emergency) to 7 (debug); lower numbers are more severe and should be forwarded to central collectors.
- Duplex mismatch symptoms
- Late collisions, FCS and runts counters, and poor throughput on one side typically indicate a half-duplex and full-duplex mismatch.
- Bottom-up troubleshooting
- Starting diagnosis at the physical layer and moving upward through data link, network, and application layers until the fault is isolated.
- Voice quality thresholds
- Acceptable interactive voice generally needs one-way latency under 150 ms, jitter under 30 ms, and packet loss under one percent.
- DHCP DORA sequence
- Client broadcasts Discover, server sends Offer, client sends Request, server sends Acknowledge, completing address assignment over four messages.
- DHCP relay agent
- A router function that forwards DHCP messages between clients and a server on another subnet, filling the gateway address field so the correct pool is used.
- PAT overload
- A NAT variant that maps many internal addresses to one public address using unique source port numbers to distinguish sessions.
- DNS CNAME record
- An alias record that points one hostname to another canonical name, commonly used for service names and third-party hosted endpoints.
- DSCP marking
- A six-bit field in the IP header used to classify packets into per-hop behaviors, set at the trust boundary and honored by QoS policies.
- NETCONF datastores
- The running, candidate, and startup stores hold configuration; the candidate store allows validation and commit before changes take effect.
- YANG data model
- A schema language that defines the structure, types, and constraints of configuration and state data exposed by NETCONF and RESTCONF interfaces.
- Idempotent automation
- A property where running the same task repeatedly produces the same end state, making playbooks safe to rerun after partial failures.
- Model-driven telemetry
- A push-based monitoring approach that streams structured device data continuously over gNMI or similar protocols instead of periodic SNMP polling.
- Change management process
- A controlled workflow of request, risk review, approval, scheduled implementation, validation, and documented backout for network changes.
- Risk treatment options
- Organizations can avoid, mitigate, transfer, or accept a risk; accepted residual risk must be documented and approved by an accountable owner.
- Incident response phases
- Preparation, detection and analysis, containment, eradication, recovery, and lessons learned, with evidence preserved under chain of custody.
- SLA versus SLO versus SLI
- An SLA is a contractual commitment, an SLO is an internal target, and an SLI is the measured indicator used to judge performance.