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NSE4 · domain

Firewall Policies and NAT

Practise NSE4 NAT and PAT questions covering address translation types, inside/outside interface roles, static vs dynamic vs PAT, and troubleshooting missing or incorrect translations.

76 questions16 easy37 medium23 hard

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What this domain covers

What to know about Firewall Policies and NAT

NAT questions usually test how private addresses are translated, when to use static NAT, dynamic NAT or PAT, and how inside/outside interfaces affect traffic flow.

Static NAT, dynamic NAT and PAT behaviour.

Inside local, inside global, outside local and outside global address meanings.

How NAT affects connectivity between private networks and public destinations.

How to troubleshoot NAT rules, ACL matches and interface direction.

Why learners struggle

Why Firewall Policies and NAT questions are commonly missed

NAT questions are missed when learners confuse the four address types (inside local, inside global, outside local, outside global) or misapply the interface direction. A translation rule can look correct but still fail if the ACL, interface, or direction is wrong.

  • ·Inside local vs inside global — inside local is the private source, inside global is the translated public address
  • ·PAT overloads — many sources share one public IP using unique port numbers
  • ·Interface direction — ip nat inside and ip nat outside must be on the correct interfaces
  • ·Static NAT vs dynamic NAT vs PAT — each serves a different use case
  • ·The NAT ACL identifies traffic to translate, not traffic to permit or deny
  • ·A missing translation can look like a routing problem if the interfaces are misconfigured

Watch out for

Common Firewall Policies and NAT exam traps

  • PAT allows many inside hosts to share one public address by using port numbers.
  • NAT rules depend on correct inside and outside interface configuration.
  • The ACL used for NAT identifies traffic to translate; it is not always a security filtering ACL.
  • Static NAT maps one private address to one public address, while PAT overloads translations.

Question index

All Firewall Policies and NAT questions (76)

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1

A FortiGate has two firewall policies: Policy ID 1 (source: 10.0.1.0/24, destination: 203.0.113.0/24, action: allow, NAT: enabled) and Policy ID 2 (source: 10.0.1.0/24, destination: all, action: allow, NAT: enabled, IP pool: pool1). A user from 10.0.1.10 sends traffic to 203.0.113.5. Which policy will the traffic match and why?

Hard
2

An administrator needs to block access to specific websites based on their FQDN (e.g., *.example.com). The FortiGate should match the destination domain regardless of the IP address the domain resolves to. Which type of address object should the admin use in the firewall policy destination?

Easy
3

An organization has a FortiGate with two internet connections (WAN1 and WAN2). They want traffic to a specific web service (203.0.113.50 port 443) to always exit via WAN2. All other internet traffic should use WAN1. Which feature should be used to achieve this?

Hard
4

An administrator has configured a firewall policy that allows outbound traffic from a subnet to the internet, with NAT enabled. The external IP is 203.0.113.1. However, the administrator wants all traffic from a specific internal server (10.0.0.10) to appear with source IP 203.0.113.2. What should the administrator do?

Medium
5

A FortiGate administrator is configuring a Virtual IP (VIP) to allow external users to access an internal web server (192.168.1.10) using the public IP 203.0.113.10 on port 80. The admin creates a VIP with mapped IP 192.168.1.10 and port 80. A firewall policy is created from WAN to DMZ with destination set to the VIP. External users report that they can access the web server. What additional step is needed to allow the internal server to respond correctly?

Medium
6

An admin configures a VIP to map public IP 203.0.113.10 to internal server 10.0.1.100 on port 80. External users can reach the server via the public IP. However, internal users cannot access the server using the public IP. What is the MOST likely cause?

Medium
7

An administrator needs to allow traffic from a guest network (192.168.100.0/24) to the internet only during business hours (Mon-Fri, 08:00-18:00). The administrator creates a schedule object and applies it to the firewall policy. However, guests can still access the internet outside of the schedule. What is the most likely cause?

Hard
8

An admin runs 'diagnose sys session filter dport 443' and sees output showing sessions with 'proto=6' and 'expire=3599'. The admin notices that these sessions are not being cleaned up after the firewall policy that allowed them is deleted. What is the reason?

Medium
9

A company has a FortiGate with two ISPs: wan1 (primary) and wan2 (backup). They want all outbound traffic from internal users to use wan1, and if wan1 fails, traffic should automatically fail over to wan2. The administrator configures static routes: default route via wan1 gateway with distance 10 and default route via wan2 gateway with distance 20. They also configure an SD-WAN zone with both interfaces and set a strategy of 'Manual' with 'Best Quality' for wan1. After testing, failover does not occur when wan1 goes down. What is the most likely reason?

Easy
10

A FortiGate admin needs to allow inbound HTTPS traffic to a web server while also applying an application control profile to block certain web applications. The web server has a VIP configured. Which TWO components are necessary for this configuration?

Medium
11

An admin runs the command 'diagnose firewall iprope list 100000' and sees the following output: id=2000000000 action=deny flag=0x0 src-interface=any dst-interface=any proto=0 src-addr=0.0.0.0-255.255.255.255 dst-addr=0.0.0.0-255.255.255.255 What does this entry represent?

Hard
12

An administrator configures a Central SNAT policy to translate traffic from the internal network (10.0.0.0/8) to the internet using the IP pool 'pool1'. The administrator also has a firewall policy that uses policy-based NAT with an IP pool 'pool2'. Both policies match the same traffic. Which NAT will be applied?

Hard
13

An administrator configures a Virtual IP (VIP) to map public IP 203.0.113.10 to internal server 10.0.1.10 on port 443. The firewall policy uses the VIP as the destination address. External users report they cannot connect. The administrator checks the policy and sees the destination interface is 'wan1' and source interface is 'wan1'. What is the most likely issue?

Hard
14

An administrator needs to block traffic from a specific geographic region (e.g., country) from reaching the corporate web server. Which type of address object should be used to define the source?

Medium
15

A FortiGate has a policy that matches traffic from LAN to WAN with NAT enabled and an IP pool. The pool contains IPs 203.0.113.1 to 203.0.113.5. The administrator notices that all traffic appears to come from 203.0.113.1. Which THREE reasons could explain this?

Hard
16

A FortiGate has a policy that enables NAT with an IP pool that uses overload (port address translation). The administrator notices that some applications are failing because they require a fixed source port range. What should the administrator do to resolve this?

Hard
17

An administrator needs to configure a firewall policy that allows internal users to access a specific web server on the internet using its domain name. The web server's IP address may change. Which type of address object should be used as the destination in the policy?

Medium
18

An administrator runs 'diagnose sys session filter dport 443' and sees the following output: proto=6 proto_state=01 duration=3600 expire=3599 What does this indicate about the session?

Medium
19

An admin is configuring a policy-based NAT rule (central NAT) to translate internal users' source IPs to the external IP of the FortiGate interface. However, users complain that some applications fail. The admin notices that the NAT rule is using 'dynamic IP pool' with overload. What is the MOST likely cause of the application failures?

Hard
20

A FortiGate administrator observes that traffic from a specific subnet is being denied even though there is an allow policy for that subnet. The administrator checks the policy list and sees an explicit deny policy above the allow policy. What should the administrator do to allow the traffic?

Medium
21

An administrator configures a policy-based NAT rule to translate traffic from 10.0.0.0/8 to 203.0.113.1 using an IP Pool with overload. Later, they also enable Central SNAT for the same traffic. The traffic is not being NAT'd as expected. What is the MOST likely reason?

Hard
22

A FortiGate admin creates a new firewall policy with source address object 'Internal_Net' and destination 'All'. After saving, traffic from 'Internal_Net' is not matching the new policy but instead matches an older policy with a broader source. What is the MOST likely cause?

Medium
23

An admin wants to block all traffic from the internet to a specific internal server except for the IP address 203.0.113.50. Which firewall policy configuration achieves this using the principle of least privilege?

Easy
24

A junior admin is creating firewall policies and wants to ensure that all traffic not explicitly permitted is denied. Which FortiGate mechanism provides this behavior by default?

Easy
25

An admin wants to block access to malicious websites using FortiGuard Web Filtering. Which policy configuration is necessary to apply the web filter profile to HTTP/HTTPS traffic?

Medium
26

An administrator wants to allow SSH access from the internet to a server inside the network at 192.168.1.10. Which NAT configuration is needed?

Easy
27

A FortiGate admin has configured a firewall policy allowing traffic from the internal network (10.0.1.0/24) to the internet (any). Users report that they cannot access a specific website (203.0.113.5). The admin runs 'diagnose firewall fqdn list' and sees that the FQDN object used in a policy above the allow policy resolves to an IP that includes 203.0.113.5. What is the MOST likely cause?

Medium
28

An administrator needs to allow outbound DNS traffic (UDP port 53) from multiple internal subnets to the internet. Which object type should be used to group the subnets into a single source in the firewall policy?

Easy
29

A FortiGate admin configures a firewall policy to allow HTTP traffic from the internal network (10.0.0.0/8) to the internet. Users report that they cannot access web pages. The admin runs 'diagnose debug flow' and sees packets hitting the policy but being dropped. What is the MOST likely cause?

Medium
30

A FortiGate administrator wants to ensure that traffic from the internal network to the internet is translated to a single public IP address. Which NAT method should be used?

Easy
31

You run 'diagnose sys session filter dport 443' and see the following output: proto=6 proto_state=01 duration=3600 expire=3599 What does this indicate?

Medium
32

A company has a web server in the DMZ that must be accessible from the internet on both HTTP and HTTPS. The admin configures a VIP to map the public IP to the server's private IP. However, external users can only reach HTTP. What is the MOST likely cause?

Medium
33

A FortiGate administrator needs to allow inbound HTTPS traffic to a web server located at 192.168.1.10. The public IP is 203.0.113.5. The administrator wants to translate the destination to the internal server and also translate the source port to a fixed range for logging purposes. Which THREE configuration elements are required?

Medium
34

What is the order of evaluation for firewall policies on a FortiGate?

Easy
35

A company uses FSSO (Fortinet Single Sign-On) with a domain controller. Users authenticate to the domain, and the FortiGate retrieves the login events. The firewall policy uses the FSSO group. Some users report that after logging in, they cannot access resources that require authentication. The administrator checks the FSSO status and sees that the FortiGate is receiving login events. What is the most likely cause?

Medium
36

A FortiGate administrator is configuring a policy-based routing (PBR) rule to send all traffic from the 'Engineering' VLAN (10.1.0.0/16) to a dedicated internet link through gateway 203.0.113.1. The administrator also wants to apply a traffic shaper to limit bandwidth. Which THREE configuration tasks must be performed?

Hard
37

An admin is troubleshooting why traffic from a specific host (10.0.1.10) to a web server (203.0.113.50:80) is being denied. The FortiGate has several policies. Which TWO CLI commands should the admin use to identify which policy is matching the traffic? (Choose two.)

Medium
38

An admin configures a firewall policy to allow SMTP traffic from a mail server to the internet with NAT enabled. External recipients report that the email source IP is the FortiGate's external interface IP. The admin wants the source to be a specific IP from a pool. What should the admin configure?

Medium
39

A FortiGate administrator is troubleshooting why traffic from a specific internal host is not being allowed through a firewall policy. The policy appears correct and is enabled. Which TWO diagnostic commands could the administrator use to determine if the traffic is matching a different policy?

Medium
40

An admin configures a policy-based NAT rule (central SNAT) to translate source IPs from 10.0.0.0/24 to a dynamic IP pool of 203.0.113.1-203.0.113.10 with overload enabled. Users report that some connections are dropped. What is the MOST likely cause?

Hard
41

A network administrator has configured a firewall policy allowing traffic from the internal network (10.0.0.0/8) to the internet. Users report that some websites are not loading. The administrator runs 'diagnose firewall iprope list 100000' and sees the policy listed with a hit count of zero. What is the MOST likely cause?

Medium
42

An admin needs to translate the source IP of traffic from multiple internal hosts to a single public IP when accessing the internet, while keeping track of each session. Which NAT method should be used?

Easy
43

A FortiGate administrator has configured a firewall policy allowing HTTP traffic from the internal network (10.0.1.0/24) to the DMZ server (192.168.1.10). The policy is placed after a deny-all policy that blocks traffic from internal to DMZ. Even though the allow policy is more specific, traffic is still being denied. What is the most likely cause?

Medium
44

An admin is configuring a policy-based NAT (central SNAT) to translate internal users to a pool of public IPs using overload. The admin wants to ensure that specific applications using non-standard ports are not affected by NAT. Which THREE steps should the admin consider?

Hard
45

A network admin runs 'diag sys session filter proto 6' and 'diag sys session list' and sees many sessions with state 'SYN_SENT' to a public web server. The firewall policy allows TCP/443. What is the MOST likely cause?

Medium
46

Which statement best describes the 'implicit deny' policy on a FortiGate?

Easy
47

A FortiGate with multiple WAN interfaces uses policy-based routing (PBR) to route traffic from subnet 10.0.0.0/24 through port1 and 10.0.1.0/24 through port2. However, traffic from 10.0.0.0/24 is still using port2. The PBR rule appears correctly configured. What is the MOST likely issue?

Hard
48

A FortiGate administrator configures a firewall policy to allow HTTP traffic from internal users to the internet. The policy uses source address 'internal_subnet', destination address 'all', and service 'HTTP'. After applying the policy, users report they cannot access websites. What is the most likely cause?

Easy
49

A FortiGate admin wants to ensure that traffic from the internal network (192.168.1.0/24) to the internet uses a specific public IP (203.0.113.10) for source NAT, and that the same public IP is also used for inbound connections to an internal web server (10.0.1.10) on port 443. Which TWO configurations are required? (Choose two.)

Medium
50

An administrator needs to apply traffic shaping to limit bandwidth for video streaming traffic on a firewall policy. Which configuration step is required?

Medium
51

A company needs to allow inbound HTTPS traffic from the internet to a web server behind the FortiGate. The public IP is 203.0.113.10, and the internal server is 192.168.1.10. The server must receive the original source IP of the client. Which THREE configurations are required to achieve this?

Hard
52

A FortiGate administrator wants to ensure that traffic from the 192.168.1.0/24 network to the internet is translated to a single public IP address using overload (PAT). Which NAT configuration should be used?

Medium
53

A FortiGate administrator wants to ensure that traffic from the internal network to an external FTP server uses a specific source IP address (203.0.113.10). The internal network uses RFC 1918 addresses. Which NAT configuration should be used?

Medium
54

An administrator creates a firewall policy with a traffic shaper to limit bandwidth for guest wireless users. After applying the policy, users can still consume high bandwidth. The administrator confirms the policy is matching. What is the MOST likely reason the traffic shaper is not effective?

Medium
55

A FortiGate has the following policy list: ID 1: allow from trust to untrust, source 10.0.0.0/24, destination all, service HTTP, NAT enabled. ID 2: allow from trust to untrust, source 10.0.1.0/24, destination all, service ALL, NAT enabled. A host 10.0.1.50 sends an HTTP request to 203.0.113.5. Which policy matches?

Hard
56

An admin wants to block all traffic from a specific geographic region. Which address object type should be used in the firewall policy source?

Medium
57

A company has a web server in the DMZ that needs to be accessible from the internet on port 443 (HTTPS). The administrator configures a Virtual IP (VIP) mapping the public IP 203.0.113.10 to the private IP 10.0.1.10 port 443. Which firewall policy is required to allow inbound traffic?

Medium
58

A FortiGate administrator needs to create a firewall policy that allows traffic from the internal network (10.0.0.0/8) to a public web server (203.0.113.10) on port 443. The policy must also perform source NAT using the FortiGate's external IP (198.51.100.1). Which NAT configuration should be applied?

Medium
59

A company has a FortiGate with multiple VDOMs. An admin creates a firewall policy in the root VDOM to allow traffic from a subnet to the internet. The traffic is not matching the policy. What is the most likely cause?

Medium
60

An administrator wants to ensure that traffic from the engineering department (subnet 192.168.10.0/24) to the internet uses a specific public IP address for source NAT. Additionally, traffic from the marketing department (192.168.20.0/24) should use a different public IP. Which method should be used?

Medium
61

A FortiGate admin is troubleshooting an issue where traffic from a specific internal host (10.0.1.50) to the internet is not being NATed as expected. The firewall policy has NAT enabled with an IP pool of type Overload. Which TWO conditions could cause the traffic to bypass the IP pool?

Medium
62

Which statement best describes the implicit deny policy at the end of a FortiGate policy list?

Easy
63

A FortiGate administrator needs to ensure that all internal users (10.0.0.0/8) accessing the internet use a single public IP address 203.0.113.10 for source NAT. Which NAT configuration should be used?

Easy
64

A network administrator configures a firewall policy allowing HTTP traffic from the internal network (10.0.0.0/8) to the internet. After applying the policy, users report they can browse the web, but the FortiGate logs show that all sessions are using the 'implicit deny' policy ID 0. What is the most likely cause?

Medium
65

A FortiGate admin configures a firewall policy to allow outbound HTTP traffic and applies a web filter profile. The admin notices that some users can access a known malicious URL while others are blocked. All users are in the same source subnet (10.0.1.0/24). What is the MOST likely cause of this inconsistent behavior?

Hard
66

Which of the following statements about FortiGate policy lookup order is correct?

Easy
67

Which of the following best describes a Virtual IP (VIP) in FortiGate?

Easy
68

An administrator configures a firewall policy with a schedule object that is set to 'Available: Mon-Fri 09:00-17:00'. At 10:00 AM on Saturday, users report they cannot access the resource. The administrator checks the policy list and sees the policy is enabled. What is the MOST likely reason?

Hard
69

A FortiGate has policy-based NAT enabled. The admin wants to translate the source IP of internal users to the interface IP for internet traffic. The firewall policy has NAT enabled. However, traffic from the internal network to the internet shows the original source IP instead of the interface IP. What is the MOST likely reason?

Hard
70

An administrator configures a firewall policy with a schedule that allows traffic only during business hours (Monday to Friday, 09:00-18:00). At 17:55 on a Friday, a user establishes an SSH session that is still active at 18:05. What happens to the session when the schedule ends?

Medium
71

Which of the following is the default action of a FortiGate firewall policy if no policy matches the traffic?

Easy
72

A network administrator creates a firewall policy allowing HTTP traffic from the internal network to a web server in the DMZ. Users report that they cannot access the web server. The administrator runs 'diagnose firewall iprope list' and sees the policy is present. What is the MOST likely cause of the issue?

Medium
73

A FortiGate administrator configures a policy-based NAT using an IP pool with type 'Fixed Port Range' for internal users accessing a specific external server. Users report that after some time, they cannot establish new connections to the server. 'diagnose ip pool list' shows many entries with 'used_port=65535'. What is the MOST likely cause?

Hard
74

An administrator is configuring a VIP to map a public IP to an internal server. The server hosts both HTTP and HTTPS services. The admin creates a VIP with port forwarding for port 80 to internal port 80, and another VIP for port 443 to internal port 443. Both VIPs use the same public IP. Users can access HTTP but not HTTPS. What is the most likely issue?

Hard
75

An admin configures a VIP to map a public IP to an internal server. The firewall policy uses the VIP as the destination. External users can access the server, but the server's logs show the source IP as the FortiGate's internal interface IP instead of the original client IP. Why is this happening?

Hard
76

A company uses FortiGate with firewall policies to control access between internal VLANs. Users in VLAN 10 report they can access internet but cannot reach a server in VLAN 20 on port 443. The server is reachable from other VLANs. The administrator checks the firewall policy configuration: there is a policy from VLAN10 to VLAN20 allowing HTTPS, with NAT disabled and logging enabled. The policy has a schedule set to 'Always'. The administrator also checks that there are no overlapping policies. What is the most likely cause?

Hard

Frequently asked questions

What does the Firewall Policies and NAT domain cover on the NSE4 exam?
NAT questions usually test how private addresses are translated, when to use static NAT, dynamic NAT or PAT, and how inside/outside interfaces affect traffic flow.
How many questions are in this domain?
This page lists all 76 Firewall Policies and NAT questions in the NSE4 question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
What is the best way to practise this domain?
Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
Can I practise only Firewall Policies and NAT questions?
Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.
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