JN0-351 Exam Dumps : Enterprise Routing and Switching Specialist (JNCIS-ENT)

The DHCP snooping feature in Juniper Networks’ EX Series switches works by building a binding database that maps the IP address, MAC address, lease time, binding type, VLAN number, and interface information 1 .  This database is used to filter and validate DHCP messages from untrusted sources 1 .

However, there are certain conditions that could prevent entries from being automatically created in the snooping database for an interface:

MAC limiting: If MAC limiting is enabled on the interface, it could potentially interfere with the operation of DHCP snooping.  MAC limiting restricts the number of MAC addresses that can be learned on a physical interface to prevent MAC flooding attacks 1 . This could inadvertently limit the number of DHCP clients that can be learned on an interface, thus preventing new entries from being added to the DHCP snooping database.

Static IP address : If the device connected to the interface is configured with a static IP address, it will not go through the DHCP process and therefore will not have an entry in the DHCP snooping database 1 .  The DHCP snooping feature relies on monitoring DHCP messages to build its database 1 , so devices with static IP addresses that do not send DHCP messages will not have their information added.

Therefore, options B and C are correct.  Options A and D are not correct because performing a DHCPRELEASE would simply remove an existing entry from the database 1 , and Dynamic ARP inspection (DAI) uses the information stored in the DHCP snooping binding database but does not prevent entries from being created 1 .

In Rapid Spanning Tree Protocol (RSTP), there are several port roles that determine the behavior of the port in the spanning tree 1 2 3 .  The roles include root, designated, alternate, backup, and disabled 1 2 3 .

The discarding state is associated with the backup, alternate, and disabled roles 1 2 3 .  In a stable topology with consistent port roles throughout the network, RSTP ensures that every root port and designated port immediately transition to the forwarding state while all alternate and backup ports are always in the discarding state 2 .  Disabled ports are also in the discarding state 3 .

Therefore, options B, C, and D are correct.

The output of the show bgp neighbor command shows the following information:

The local AS number of R1 is 65400, as indicated by the line “Local: 10.32.1.1+179 AS 65400”.

The peer AS number of 10.32.1.2 is 63645, as indicated by the line “Peer: 10.32.1.2+179 AS 63645”.

The BGP session is established, as indicated by the line “State: Established”.

The routers are exchanging IPv4 routes, as indicated by the line “Type: External State: Established Flags: < Sync > ” and the table showing the number of prefixes received and sent for inet.0 routing table. References:  Enterprise Routing and Switching, Specialist (JNCIS-ENT) - Juniper Networks , [show bgp neighbor - Technical Documentation - Support - Juniper Networks]