Download 2023 SONiC Hackathon Winner Practice Exam and more Exams Technology in PDF only on Docsity!
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Question 1. Which component in SONiC provides the vendor‑agnostic abstraction for hardware resources? A) orchagent B) syncd C) Switch Abstraction Interface (SAI) D) Redis database Answer: C Explanation: SAI defines a standard API that allows SONiC to control different ASICs without vendor‑specific code. Question 2. In SONiC, what is the primary purpose of the Redis “State” database? A) Storing user credentials B) Persisting routing tables C) Exchanging operational state between microservices D) Logging system events Answer: C Explanation: The State DB holds runtime state data that microservices read/write to coordinate actions. Question 3. Which microservice is responsible for translating high‑level configuration changes into SAI commands? A) syncd B) orchagent C) bgp daemon (bgpd) D) gNMI server Answer: B
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Explanation: orchagent watches Config DB changes and issues appropriate SAI calls via syncd. Question 4. What container runtime does SONiC use to host its microservices? A) rkt B) LXC C) Docker D) Podman Answer: C Explanation: SONiC packages each daemon in a Docker container for isolation and easy upgrades. Question 5. Which CLI framework is used by SONiC for its command‑line interface? A) Bash B) Klish C) Zsh D) Fish Answer: B Explanation: Klish provides a structured, hierarchical CLI that maps directly to SONiC’s DB schema. Question 6. SONiC‑YANG primarily serves what function? A) Generating traffic patterns B) Defining data models for configuration and state C) Encrypting management traffic D) Monitoring hardware temperature
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C) Using “bgp‑large‑community” to aggregate prefixes D) Activating “bgp‑memory‑limit” with per‑VRF quotas Answer: D Explanation: Setting memory limits per VRF prevents a single BGP instance from exhausting system RAM. Question 10. BGP unnumbered is most beneficial in which scenario? A) IPv6‑only data centers B) High‑density top‑of‑rack switches with limited IP space C) Legacy MPLS networks D) WAN edge routers with static routes Answer: B Explanation: Unnumbered BGP allows interfaces to share a single loopback IP, conserving address space. Question 11. Which feature enables a device to connect to an EVPN fabric with multiple uplinks for redundancy? A) VLAN stacking B) EVPN multi‑homing C) Static ARP entries D) OSPF cost tuning Answer: B Explanation: Multi‑homing allows a leaf to attach to multiple spine switches while maintaining a single EVPN instance. Question 12. In SONiC, VLAN configuration is stored in which database?
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A) APPL_DB
B) STATE_DB
C) CONFIG_DB
D) COUNTERS_DB
Answer: C Explanation: CONFIG_DB holds persistent configuration objects such as VLAN definitions. Question 13. What is the purpose of a “virtual port” in SONiC? A) Emulating a physical interface for testing or container connectivity B) Providing out‑of‑band management only C) Enabling PoE power delivery D) Managing SNMP traps Answer: A Explanation: Virtual ports act as software‑only interfaces used for labs, containers, or overlay tunnels. Question 14. The “Stack Overflow” log analyzer introduced in the 2023 winner hackathon primarily helps with: A) Detecting memory leaks in Docker containers B) Parsing crash logs to pinpoint root causes automatically C) Generating configuration backups D) Monitoring CPU utilization trends Answer: B Explanation: It automates log parsing to accelerate troubleshooting of system crashes.
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Explanation: Exporters expose metrics that Prometheus scrapes; Grafana visualizes them for real‑time health. Question 18. KUBE2SONIC is designed to monitor SONiC services running inside: A) VirtualBox VMs B) Kubernetes pods C) Bare‑metal servers only D) OpenStack Nova instances Answer: B Explanation: It provides visibility of SONiC containers orchestrated by Kubernetes. Question 19. Aggregate VoQ counters are primarily used to monitor: A) CPU temperature B) Deep‑buffer switch queue utilization across multiple ports C) License compliance D) Power supply health Answer: B Explanation: VoQ aggregates per‑port queue stats, helping detect congestion in high‑throughput environments. Question 20. SONiC Secure Central centralizes which type of policy? A) QoS shaping rules B) Security policies such as ACLs and authentication methods C) BGP MED values D) LLDP neighbor discovery settings
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Answer: B Explanation: It provides a single point to define and distribute security configurations across the fabric. Question 21. A known vulnerability in RADIUS/TACACS+ NSS integration can lead to: A) Unauthorized configuration changes via name‑service spoofing B) Packet duplication in the data plane C) Loss of VLAN tagging D) Incorrect OSPF LSAs Answer: A Explanation: NSS vulnerabilities allow attackers to manipulate authentication lookups, compromising access control. Question 22. Password hardening in SONiC typically enforces which of the following? A) Minimum length, complexity, and periodic rotation B) Plain‑text storage for faster login C) Unlimited failed login attempts D) Single‑factor authentication only Answer: A Explanation: Strong password policies improve access security by requiring complexity and regular changes. Question 23. The Terraform provider for SONiC enables which operation? A) Direct hardware flashing via USB B) Automated provisioning and configuration of switches as code C: Manual CLI editing only
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C) High‑performance routers with MPLS D) Legacy Cisco Catalyst switches Answer: A Explanation: Campus deployments often use commodity hardware that runs OpenWiFi alongside SONiC. Question 27. Nephio’s role in RAN environments is to: A) Provide a GUI for BGP policy editing B) Orchestrate virtualized Cloud Service Routers (vCSR) on SONiC nodes C) Replace SONiC’s SAI layer D) Manage DHCP lease pools only Answer: B Explanation: Nephio automates deployment of vCSRs, enabling cloud‑native RAN connectivity. Question 28. Priority Flow Control (PFC) in lossless Ethernet primarily protects which traffic type? A) HTTP web traffic B) RoCEv2 (RDMA over Converged Ethernet) C) SMTP email traffic D) DNS queries Answer: B Explanation: PFC provides per‑priority pause frames to prevent loss of latency‑sensitive RDMA traffic. Question 29. When configuring PFC headroom recommendations, which factor is most critical?
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A) Number of VLANs configured B) Expected burst size of lossless traffic per priority C) CPU clock speed D) Number of static routes Answer: B Explanation: Headroom must accommodate the maximum burst of lossless traffic to avoid pause‑induced congestion. Question 30. Mapping EXP to TC in SONiC ensures: A) Consistent QoS treatment of tunneled traffic across the fabric B) Automatic IP address assignment C) Encryption of management traffic D) Faster BGP convergence Answer: A Explanation: EXP (DSCP) values carried in tunnels are translated to internal Traffic Classes for QoS enforcement. Question 31. Overlay ECMP in SONiC is used to: A) Balance traffic across multiple underlay paths with equal cost B) Duplicate packets for redundancy C) Disable VLAN tagging on tunnels D) Encrypt overlay traffic Answer: A Explanation: ECMP spreads flows over several equal‑cost overlay paths, improving utilization and resilience.
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Explanation: It replays saved FPM events, allowing engineers to reproduce and debug forwarding issues. Question 35. Auto‑detection of FEC in SONiC occurs during which event? A) System boot and link up/down transitions B) CLI login only C) Static route configuration D) BGP neighbor establishment Answer: A Explanation: SONiC negotiates Forward Error Correction automatically when links become active. Question 36. Which microservice is responsible for managing the Redis databases themselves? A) redis‑server container B) orchagent C) syncd D) bgpd Answer: A Explanation: The Redis server runs in its own container and provides the DB back‑end for other services. Question 37. In SONiC, which database holds operational state such as interface counters? A) CONFIG_DB B) STATE_DB C) APPL_DB
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D) COUNTERS_DB (part of STATE_DB) Answer: D Explanation: COUNTERS_DB is a namespace within STATE_DB that stores real‑time stats. Question 38. What is the effect of enabling “bgp‑bestpath‑selection‑algorithm” to “router‑id‑tiebreaker” in SONiC? A) It prefers routes with the lowest router ID when other attributes tie B) It disables route reflection C) It forces all routes to be advertised to all peers D) It increases BGP keepalive interval Answer: A Explanation: The router‑ID tiebreaker resolves equal‑cost BGP paths by comparing router IDs. Question 39. Which of the following best describes the function of “syncd” in SONiC? A) It synchronizes SAI state with the ASIC hardware based on commands from orchagent B) It provides a web UI for configuration C) It runs BGP routing protocols only D) It stores user passwords securely Answer: A Explanation: syncd receives SAI calls from orchagent and applies them to the ASIC, keeping hardware in sync. Question 40. When configuring EVPN Type‑5 routes, which attribute determines the next‑hop reachability? A) Route‑Distinguisher (RD) B) Ethernet Segment Identifier (ESI)
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B) Changing the BGP hold‑time value C) Modifying the maximum number of BGP peers D) Enabling IPv6 support only Answer: A Explanation: Larger pipeline sizes batch more updates, reducing round‑trip overhead. Question 44. Which of the following is a key benefit of using “BGP unnumbered” on leaf switches? A) Eliminates the need for loopback addresses for BGP sessions B) Increases MPLS label space C) Forces all routes to be IPv6 only D) Disables ECMP usage Answer: A Explanation: Unnumbered BGP allows interfaces to use a shared loopback address, saving IP resources. Question 45. What role does the “veth” pair play in SONiC’s container networking? A) Provides a virtual Ethernet link between the host and a container for management traffic B) Acts as a physical uplink to the ASIC C) Stores configuration files persistently D) Generates random MAC addresses for interfaces Answer: A Explanation: veth pairs connect containers to the host namespace, enabling communication with other services.
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Question 46. Which SONiC component is responsible for applying QoS policies defined in CONFIG_DB to hardware queues? A) qos daemon (qosd) B) syncd C) orchagent D) bgpd Answer: C Explanation: orchagent watches QoS objects in CONFIG_DB and instructs syncd to program the ASIC queues. Question 47. In the context of SONiC monitoring, what does “KUBE2SONIC” primarily export? A) Container health metrics to Prometheus B) Firmware version to a web portal C) VLAN IDs to a DHCP server D) BGP neighbor tables to Netconf Answer: A Explanation: It gathers container status and exposes metrics for Prometheus scrapes. Question 48. Which of the following is NOT a standard SONiC microservice? A) syncd B) orchagent C) bgpd D) ospfd‑legacy Answer: D
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D) sonic_bgp Answer: A Explanation: The sonic_interface resource allows you to set admin status, IP, and other parameters. Question 52. In Ansible, which file typically contains the inventory of SONiC devices? A) hosts.ini B) sonic.cfg C) inventory.yml D) playbook.json Answer: C Explanation: Ansible inventory can be expressed in YAML; inventory.yml lists switch hostnames and groups. Question 53. Which OpenStack service directly interacts with the SONiC ML2 driver? A) Nova compute B) Neutron networking C) Glance image service D) Cinder block storage Answer: B Explanation: Neutron uses the ML2 plugin to provision network resources on SONiC switches. Question 54. The “vlan‑member” entry in CONFIG_DB must include which attribute to be operational? A) tagging_mode (tagged/untagged) B) mtu size
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C) router_id D) bgp_asn Answer: A Explanation: tagging_mode defines whether the VLAN member is tagged or untagged on the port. Question 55. Which SONiC daemon is responsible for managing the Link Aggregation Control Protocol (LACP)? A) lacpd B) syncd C) bgpd D) orchagent Answer: A Explanation: lacpd handles LACP negotiation and aggregation state. Question 56. The “auto‑detect‑fec” feature in SONiC can be overridden by which configuration knob? A) fec_mode set to none in INTERFACE table B) bgp_fec in BGP table C) vlan_fec in VLAN table D) qos_fec in QoS profile Answer: A Explanation: Setting fec_mode to none disables auto‑detection for that interface. Question 57. In the context of SONiC’s security hardening, which file stores the hashed passwords for local users?
