JNCIA Firewall Filters 3

Question 1

What is the primary reason for applying a Junos firewall filter to the loopback (lo0) interface?

Accepted Answer

To protect the Routing Engine from unwanted or malicious control-plane traffic

Answer

Applying a filter to lo0 restricts traffic destined for the Routing Engine itself, protecting the control plane from DoS attacks and unauthorized access.

Question 2

Which Junos operational command displays firewall filter match counts and packet counters?

Accepted Answer

show firewall

Answer

The 'show firewall' command displays counters for all configured firewall filters, including term-level packet and byte counts.

Question 3

Which action modifier in a Junos firewall filter term stores a short record of the packet header in a local buffer for later review?

Accepted Answer

log

Answer

The 'log' action modifier stores packet header information in the Routing Engine's firewall log buffer, viewable with 'show firewall log'.

Question 4

In what order does Junos evaluate the terms within a firewall filter when a packet is received?

Accepted Answer

Terms are evaluated sequentially in the order they were configured

Answer

Junos evaluates firewall filter terms in the exact order they appear in the configuration, stopping at the first match.

Question 5

Which Junos firewall filter match condition is used to match packets that belong to an already-established TCP session (packets with ACK or RST flags set)?

Accepted Answer

tcp-established

Answer

The 'tcp-established' match condition matches TCP packets with the ACK or RST flag set, which indicates they are part of an existing session.

JNCIA - Juniper Networks Certified Internet Associate Practice Test

JNCIA - Juniper Networks Certified Internet Associate Practice Test

JNCIA Firewall Filters 3