JN0-352 Exam Dumps and Practice Questions

Configuring interface-type p2p under an OSPF interface tells Junos to treat that interface as a point-to-point network type regardless of the underlying physical medium, which removes the interface from the standard broadcast-network state machine entirely. On a true broadcast network, two routers must first complete a Designated Router and Backup Designated Router election, wait through the associated timers, and only then proceed through 2-Way, ExStart, Exchange, and Loading before reaching Full --- a multi-step process. A point-to-point interface skips DR/BDR election altogether and proceeds directly from 2-Way into ExStart, so adjacencies form measurably faster, which is the first correct benefit. Because there is no DR on a point-to-point interface, Junos also does not generate a Type 2 Network LSA to describe the segment; the connected subnet is instead advertised as a simple stub-network entry inside the Router LSA itself, eliminating an entire LSA type from the area's link-state database and reducing its overall size, which is the second correct benefit. Point-to-point configuration is entirely incompatible with DR election, so a router configured this way cannot 'win' a DR election --- there is no DR to win. Advertisement of the connected network happens on any operational OSPF interface irrespective of network type, so that option describes normal OSPF behavior rather than a benefit specific to the point-to-point setting. Reference topics: Junos Enterprise Routing -- OSPF Network Types, Configuring OSPF Interface Type.

A GRE-encapsulated packet consists of the original passenger packet wrapped inside a GRE header and a new outer IP delivery header, and the combined size of these two additions is what constitutes GRE's per-packet overhead. The base GRE header, as defined in RFC 2784 and used in its minimal, non-keyed, non-checksummed form (the default and most common deployment), is exactly 4 bytes in length, containing the flags/version field and the protocol type field identifying the encapsulated payload's ether type. Layered around that GRE header is a completely new outer IPv4 header, which itself consumes a standard 20 bytes, containing the tunnel source and destination addresses used for delivery across the underlying network. Adding these two components together --- 4 bytes for the GRE header plus 20 bytes for the new outer IPv4 header --- yields a total of exactly 24 bytes of overhead imposed on every encapsulated packet, which is precisely why Junos automatically sets the default protocol MTU on gr- tunnel interfaces to 1476 bytes (1500 minus 24) to prevent oversized, post-encapsulation packets from requiring fragmentation on a standard 1500-byte Ethernet path. The 20-byte figure alone describes only the new IP header in isolation and omits the GRE header itself, while 12 and 32 bytes do not correspond to any standard, non-keyed GRE encapsulation configuration and are included purely as plausible-looking distractors. Reference topics: Junos Enterprise Routing -- Tunneling, GRE Header Overhead and MTU Planning.

MACsec (IEEE 802.1AE) secures a point-to-point Ethernet link independently of how the logical unit above it is configured for VLAN tagging, so neither trunk mode nor access mode has any bearing on whether the MACsec Key Agreement (MKA) protocol can establish a secure channel. What does determine success is the pre-shared key material: when static CAK security mode is used, the Connectivity Association Key (CAK) and the Connectivity Association Key Name (CKN) must be configured identically on both ends of the link. If they do not match, MKA never completes the exchange, no secure channel is created, and all traffic on that interface is dropped rather than merely left unencrypted. Equally important, and frequently overlooked, is that MACsec adds up to 32 bytes of overhead per frame for the security tag (SecTAG) and integrity check value (ICV); Juniper's official guidance is to ensure the difference between the interface's physical MTU and the protocol MTU is large enough to absorb this overhead, or frames will be silently discarded once encryption is active, producing symptoms that look identical to a failed session. Both the CAK/CKN and MTU checks are documented first-line troubleshooting steps for MACsec on EX Series switches. Reference topics: Junos Enterprise Switching -- Layer 2 Security, Configuring and Troubleshooting MACsec on EX Series Switches.

Local preference is a well-known, discretionary BGP path attribute carried exclusively in IBGP UPDATE messages, and Junos assigns every route a local preference value of 100 by default whenever a route is received without an explicit LOCAL_PREF value already attached, or when the attribute has not been otherwise modified through routing policy. This default of 100 becomes the implicit baseline against which any administrator-configured local preference adjustments are compared. Because higher local preference values are always preferred over lower ones during BGP best-path selection --- and this evaluation happens before AS path length, origin, or MED are ever considered --- network engineers commonly use local preference specifically to steer outbound traffic leaving the autonomous system toward a preferred exit peer or upstream provider, by assigning a higher local preference to routes learned from that preferred peer relative to routes learned from alternative peers, making the third statement correct as well. Local preference is explicitly excluded from advertisement to EBGP peers under the BGP specification; it is meaningful only within the boundaries of a single AS and is stripped before a route crosses an AS boundary outward, since a neighboring AS has no reason to trust or honor another organization's internal preference values. A local preference of 0 does not have any special 'drop' semantics in BGP --- it is simply the lowest possible numeric preference value and is treated like any other value during comparison, not as a discard instruction. Reference topics: Junos Enterprise Routing -- BGP, Local Preference Defaults and Outbound Traffic Engineering.

When storm control on an EX Series switch is configured with an action of interface-shutdown (rather than the default of simply dropping excess traffic), exceeding the configured bandwidth threshold for broadcast, multicast, or unknown-unicast traffic causes Junos to administratively disable the offending interface to protect the rest of the switching fabric. Recovery from this condition can happen automatically if a recovery-timeout interval has been configured, but when immediate manual recovery is required, the operational command clear ethernet-switching recovery-timeout interface interface-name explicitly clears the storm-control-triggered violation and re-enables the port without waiting for the timer to expire. This command is purpose-built for this exact condition and is distinct from more general troubleshooting commands: clear ethernet-switching table purges the learned MAC address database and has no bearing on a storm-control-disabled port; clear interface statistics resets traffic counters for diagnostic baselining but does not touch administrative state; and clear log messages simply flushes the local system log buffer. Administrators should also verify the underlying cause of the storm --- a switching loop, a misbehaving host, or a misconfigured device --- before manually clearing the condition, since without addressing the root cause the port is likely to trip again. This command and workflow are commonly tested as part of the Layer 2 security and resiliency features on EX platforms. Reference topics: Junos Enterprise Switching -- Storm Control and Port Security, Recovering Interfaces Disabled by Storm Control.