Junos OS Fundamentals

JN0-106 · 16 questions

• A rural broadband cooperative's network team is evaluating why Junos runs the same OS image, with the same daemons and command structure, on the co-op's core routers, aggregation switches, and CPE gateways alike. Which benefit best describes this one-software-track design?
• A regional ISP's core router in its main POP experiences a Routing Engine process restart during a routine software patch, but subscribers report no interruption to traffic already flowing through existing sessions. Which aspect of Junos architecture best explains this behavior?
• A rural fiber cooperative's network engineer is asked which Junos component is responsible for actually switching subscriber traffic from an incoming interface to the correct outgoing interface at line rate, on a core aggregation router. Which component performs this function?
• A cooperative's network operations team wants to know which Junos component is responsible for running the dynamic routing protocol sessions to the co-op's upstream transit provider and building the master routing table from the routes it learns. Which component performs this role?
• While explaining Junos concepts to a new hire, a senior engineer at a regional ISP describes traffic entering one interface of a core router and leaving through another interface toward its final destination, without the router itself being the source or destination. What category of traffic is this?
• A network technician at a rural broadband cooperative learns that some packets arriving at a core router cannot simply be switched by the forwarding hardware and instead get sent up to the Routing Engine for special handling. What is this category of traffic called in Junos, and what is a defining trait of it?
• An engineer at a regional ISP is troubleshooting why a router's routing table shows several candidate paths to a subscriber aggregation subnet, while only one specific next hop is actually used to forward live traffic toward that subnet. What explains this difference?
• A rural ISP's senior engineer explains that a specific Junos process running on the Routing Engine is responsible for establishing protocol adjacencies with the co-op's peering routers and computing the best paths that populate the routing table. Which Junos daemon performs this role?
• During a hardware alarm review, a network engineer at a regional ISP's carrier-hotel POP is told that a particular Junos daemon on the Routing Engine tracks the operational status of power supplies, fan trays, and other physical chassis components and raises alarms when something fails. Which daemon is responsible for this?
• A new technician at a rural fiber cooperative asks which Junos daemon on the Routing Engine is responsible for accepting an administrator's CLI session, validating configuration syntax, and committing configuration changes. Which daemon handles this function?
• A rural ISP is bringing up a new subscriber aggregation switch, and an engineer notes that once an interface is configured with an IP address and enabled, a specific Junos daemon is responsible for applying that configuration to the actual interface and bringing it into an operational up state. Which daemon performs this role?
• A subscriber at a rural fiber cooperative runs a traceroute toward a distant website, and one of the core routers along the path needs to generate an ICMP "time exceeded" message back to the subscriber because the packet's TTL reached zero at that hop. Which category of traffic does this generated ICMP message represent from the router's own perspective?
• A regional ISP operates Juniper routers at its core, Juniper switches at subscriber aggregation sites, and a Juniper security platform at its network edge. An engineer new to Junos asks how these different device families relate architecturally. Which statement correctly describes that relationship?
• An engineer at a regional ISP is asked why a core router forwards millions of packets per second for ordinary subscriber traffic, yet a sudden flood of malformed packets requiring Routing Engine processing can noticeably slow the router's control-plane responsiveness. What architectural reason best explains this difference in behavior?
• After a static route is added to a router's configuration at a rural ISP's aggregation site and the configuration is committed, the route needs to actually be used to forward live subscriber traffic. Which sequence correctly describes how that route becomes usable for forwarding?
• A rural ISP's senior engineer explains that on a Junos router, the process handling SNMP polling can crash and restart on its own without taking down the process running BGP or the process handling the CLI. What architectural fact explains this resilience?