JNCIA-SEC Srx Series Service Gateways — Timed 10 Questions

Question 1

An administrator notices that traffic traversing an SRX300 device experiences unexpected drops. After examining the packet flow, they suspect an issue with the flow session table. Which command displays the active session table entries and their corresponding states?

10 minute time limit — choose an answer to begin.

Accepted Answer

show security flow sessions. The 'showsecurityflowsessions' command displays the active sessions currently maintained in the SRX security flow table, showing source, destination, and state.

Answer

show security flow statistics

Answer

show firewall filter

Answer

show session table active

Question 2

While troubleshooting traffic flow through an SRX Series device, you notice that packets are evaluated against security policies before a specific lookup. According to the SRX traffic flow mechanics, what is the very first action performed on an incoming packet entering an interface?

Accepted Answer

Session lookup (flow table lookup). When a packet arrives at an SRX interface, the first step in the flow processing pipeline is checking the flow table to see if a session already exists for that traffic.

Answer

Security policy lookup

Answer

NAT rule evaluation

Answer

Screen option inspection

Question 3

An administrator is deploying a new SRX Series device and needs to ensure that transit traffic passing between different security zones is inspected by the security engine. Which architecture component on the SRX Series handles stateful session tracking and security policy enforcement?

Accepted Answer

Security Forwarding Engine (SFE). The security processing on SRX Series gateways is handled by the security forwarding engine (SFE), which is powered by specialized hardware or software components like SPCs, REs, and PIMs depending on the model, running stateful inspection and security policies.

Answer

Network Processing Module (NPM)

Answer

Packet Transfer Controller (PTC)

Answer

Routing Engine (RE)

Question 4

You are configuring a secure management connection to an SRX Series device. By default, which operational management interface is isolated from the data plane routing tables and uses its own dedicated routing table?

Accepted Answer

The dedicated management interface (fxp0 / me0). The fxp0 (or me0 on some models) management interface utilizes a dedicated management routing table ('inet.0' vs routing instance management) to isolate management traffic from transit data traffic.

Answer

The internal backplane switch fabric

Answer

The high-availability control port (fab0)

Answer

The loopback interface (lo0)

Question 5

Which command allows an administrator to view the factory-default configuration or rollback to a previous configuration version on an SRX device?

Accepted Answer

rollback <number>. The 'rollback' command allows reverting the candidate configuration to a previously saved numbered configuration state.

Answer

revert configuration history

Answer

restore factory-defaults

Answer

undo last-change

Question 6

When configuring redundant physical interfaces using Link Aggregation Control Protocol (LACP) on an SRX Series gateway, what is the correct interface naming convention for aggregated Ethernet interfaces?

Accepted Answer

reth0. Aggregated Ethernet interfaces in Junos are designated with the 'ae' prefix (e.g., ae0, ae1).

Answer

ge-0/0/0

Answer

lt-0/0/0

Answer

reth0

Question 7

An administrator configures NAT on an SRX Series gateway and encounters an issue where overlapping IP spaces require destination NAT and source NAT (twice NAT) simultaneously. In what order are NAT rules evaluated in the SRX packet flow?

Accepted Answer

Destination NAT is evaluated before routing and security policy lookup, while Source NAT is evaluated later in the flow pipeline. On SRX Series devices, NAT is integrated into the packet flow in a specific sequence: Destination NAT (DNAT) is applied first, before route lookup and security policy evaluation, because the destination IP/port must be translated to determine the correct route and policy match. Source NAT (SNAT) is applied later in the flow, after the security policy lookup, just before the packet is forwarded out the egress interface. This ordering is critical for twice-NAT scenarios where overlapping address spaces require both translations.

Answer

Both NAT types are evaluated simultaneously in a single processing step.

Answer

NAT rules are only evaluated after session termination.

Answer

Source NAT is evaluated before Destination NAT

Question 8

You are configuring a security policy on an SRX device to allow traffic between two zones. Which three elements are mandatory when defining a basic security policy in Junos?

Accepted Answer

From-zone, to-zone, match criteria (source/destination/application), and then-action (permit/deny). A Junos security policy requires specifying from-zone, to-zone, source address, destination address, and application/service, along with an action.

Answer

Source zone, destination zone, and application

Answer

Routing instance, NAT pool, and security screen

Answer

Interface name, IP address, and MAC address

Question 9

You are configuring secure remote access to an SRX Series device via SSH. Which configuration hierarchy is used to restrict administrative access to specific trusted source IP addresses?

Accepted Answer

set system services ssh allow-access source-address <ip>. Administrative access services (such as SSH) and trusted source addresses are configured under 'set system services ssh'.

Answer

set security policies

Answer

set management security-zone trusted-hosts

Answer

set firewall filter management-filter

Question 10

An administrator configures IPsec VPN tunnels on an SRX Series gateway. During testing, Phase 1 negotiations fail. Which operational command should the administrator run to view detailed Phase 1 Internet Key Exchange (IKE) negotiation logs and failure reasons?

Accepted Answer

show security ike security-associations. The command 'show security ikesecurity-associations' or security ike diagnostic tracing shows IKE status and errors.

Answer

show vpn status

Answer

show crypto session

Answer

show security ipsec security-associations