DNS Overview
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Next-Generation Firewall Docs
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PAN-OS 9.1 (EoL)
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- Cloud Management of NGFWs
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- Management Interfaces
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- Launch the Web Interface
- Configure Banners, Message of the Day, and Logos
- Use the Administrator Login Activity Indicators to Detect Account Misuse
- Manage and Monitor Administrative Tasks
- Commit, Validate, and Preview Firewall Configuration Changes
- Export Configuration Table Data
- Use Global Find to Search the Firewall or Panorama Management Server
- Manage Locks for Restricting Configuration Changes
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- Define Access to the Web Interface Tabs
- Provide Granular Access to the Monitor Tab
- Provide Granular Access to the Policy Tab
- Provide Granular Access to the Objects Tab
- Provide Granular Access to the Network Tab
- Provide Granular Access to the Device Tab
- Define User Privacy Settings in the Admin Role Profile
- Restrict Administrator Access to Commit and Validate Functions
- Provide Granular Access to Global Settings
- Provide Granular Access to the Panorama Tab
- Panorama Web Interface Access Privileges
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- Reset the Firewall to Factory Default Settings
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- Plan Your Authentication Deployment
- Configure SAML Authentication
- Configure Kerberos Single Sign-On
- Configure Kerberos Server Authentication
- Configure TACACS+ Authentication
- Configure RADIUS Authentication
- Configure LDAP Authentication
- Configure Local Database Authentication
- Configure an Authentication Profile and Sequence
- Test Authentication Server Connectivity
- Troubleshoot Authentication Issues
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- Keys and Certificates
- Default Trusted Certificate Authorities (CAs)
- Certificate Deployment
- Configure the Master Key
- Export a Certificate and Private Key
- Configure a Certificate Profile
- Configure an SSL/TLS Service Profile
- Replace the Certificate for Inbound Management Traffic
- Configure the Key Size for SSL Forward Proxy Server Certificates
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- HA Overview
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- Prerequisites for Active/Active HA
- Configure Active/Active HA
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- Use Case: Configure Active/Active HA with Route-Based Redundancy
- Use Case: Configure Active/Active HA with Floating IP Addresses
- Use Case: Configure Active/Active HA with ARP Load-Sharing
- Use Case: Configure Active/Active HA with Floating IP Address Bound to Active-Primary Firewall
- Use Case: Configure Active/Active HA with Source DIPP NAT Using Floating IP Addresses
- Use Case: Configure Separate Source NAT IP Address Pools for Active/Active HA Firewalls
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT in Layer 3
- Refresh HA1 SSH Keys and Configure Key Options
- HA Firewall States
- Reference: HA Synchronization
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- Use the Dashboard
- Monitor Applications and Threats
- Monitor Block List
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- Report Types
- View Reports
- Configure the Expiration Period and Run Time for Reports
- Disable Predefined Reports
- Custom Reports
- Generate Custom Reports
- Generate the SaaS Application Usage Report
- Manage PDF Summary Reports
- Generate User/Group Activity Reports
- Manage Report Groups
- Schedule Reports for Email Delivery
- Manage Report Storage Capacity
- View Policy Rule Usage
- Use External Services for Monitoring
- Configure Log Forwarding
- Configure Email Alerts
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- Configure Syslog Monitoring
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- Traffic Log Fields
- Threat Log Fields
- URL Filtering Log Fields
- Data Filtering Log Fields
- HIP Match Log Fields
- IP-Tag Log Fields
- User-ID Log Fields
- Tunnel Inspection Log Fields
- SCTP Log Fields
- Authentication Log Fields
- Config Log Fields
- System Log Fields
- Correlated Events Log Fields
- GTP Log Fields
- Syslog Severity
- Custom Log/Event Format
- Escape Sequences
- Forward Logs to an HTTP/S Destination
- Firewall Interface Identifiers in SNMP Managers and NetFlow Collectors
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- User-ID Overview
- Enable User-ID
- Map Users to Groups
- Enable User- and Group-Based Policy
- Enable Policy for Users with Multiple Accounts
- Verify the User-ID Configuration
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- App-ID Overview
- App-ID and HTTP/2 Inspection
- Manage Custom or Unknown Applications
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- Apply Tags to an Application Filter
- Create Custom Application Tags
- Workflow to Best Incorporate New and Modified App-IDs
- See the New and Modified App-IDs in a Content Release
- See How New and Modified App-IDs Impact Your Security Policy
- Ensure Critical New App-IDs are Allowed
- Monitor New App-IDs
- Disable and Enable App-IDs
- Safely Enable Applications on Default Ports
- Applications with Implicit Support
- Application Level Gateways
- Disable the SIP Application-level Gateway (ALG)
- Maintain Custom Timeouts for Data Center Applications
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- Best Practices for Securing Your Network from Layer 4 and Layer 7 Evasions
- Set Up Antivirus, Anti-Spyware, and Vulnerability Protection
- Set Up File Blocking
- Prevent Brute Force Attacks
- Customize the Action and Trigger Conditions for a Brute Force Signature
- Enable Evasion Signatures
- Monitor Blocked IP Addresses
- Threat Signature Categories
- Create Threat Exceptions
- Custom Signatures
- Threat Prevention Resources
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- Decryption Overview
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- Keys and Certificates for Decryption Policies
- SSL Forward Proxy
- SSL Forward Proxy Decryption Profile
- SSL Inbound Inspection
- SSL Inbound Inspection Decryption Profile
- SSL Protocol Settings Decryption Profile
- SSH Proxy
- SSH Proxy Decryption Profile
- Decryption Profile for No Decryption
- SSL Decryption for Elliptical Curve Cryptography (ECC) Certificates
- Perfect Forward Secrecy (PFS) Support for SSL Decryption
- SSL Decryption and Subject Alternative Names (SANs)
- High Availability Support for Decrypted Sessions
- Decryption Mirroring
- Configure SSL Forward Proxy
- Configure SSL Inbound Inspection
- Configure SSH Proxy
- Configure Server Certificate Verification for Undecrypted Traffic
- Enable Users to Opt Out of SSL Decryption
- Temporarily Disable SSL Decryption
- Configure Decryption Port Mirroring
- Verify Decryption
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- How Decryption Broker Works
- Layer 3 Security Chain Guidelines
- Configure Decryption Broker with One or More Layer 3 Security Chain
- Transparent Bridge Security Chain Guidelines
- Configure Decryption Broker with a Single Transparent Bridge Security Chain
- Configure Decryption Broker with Multiple Transparent Bridge Security Chains
- Activate Free Licenses for Decryption Features
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- About Palo Alto Networks URL Filtering Solution
- How Advanced URL Filtering Works
- URL Filtering Use Cases
- Plan Your URL Filtering Deployment
- URL Filtering Best Practices
- Activate The Advanced URL Filtering Subscription
- Configure URL Filtering
- Test URL Filtering Configuration
- Log Only the Page a User Visits
- Create a Custom URL Category
- URL Category Exceptions
- Use an External Dynamic List in a URL Filtering Profile
- Allow Password Access to Certain Sites
- URL Filtering Response Pages
- Customize the URL Filtering Response Pages
- HTTP Header Logging
- Request to Change the Category for a URL
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- Tap Interfaces
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- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
- Zone Protection for a Virtual Wire Interface
- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure an Aggregate Interface Group
- Use Interface Management Profiles to Restrict Access
- Virtual Routers
- Service Routes
- RIP
- Route Redistribution
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- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
- Dynamic DNS Overview
- Configure Dynamic DNS for Firewall Interfaces
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- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
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- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
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- Policy Types
- Policy Objects
- Track Rules Within a Rulebase
- Enforce Policy Rule Description, Tag, and Audit Comment
- Move or Clone a Policy Rule or Object to a Different Virtual System
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- External Dynamic List
- Built-in External Dynamic Lists
- Configure the Firewall to Access an External Dynamic List
- Retrieve an External Dynamic List from the Web Server
- View External Dynamic List Entries
- Exclude Entries from an External Dynamic List
- Enforce Policy on an External Dynamic List
- Find External Dynamic Lists That Failed Authentication
- Disable Authentication for an External Dynamic List
- Register IP Addresses and Tags Dynamically
- Use Dynamic User Groups in Policy
- Use Auto-Tagging to Automate Security Actions
- CLI Commands for Dynamic IP Addresses and Tags
- Application Override Policy
- Test Policy Rules
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PAN-OS 11.1 & Later
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
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- Tap Interfaces
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- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
- Zone Protection for a Virtual Wire Interface
- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure a PPPoE Client on a Subinterface
- Configure an IPv6 PPPoE Client
- Configure an Aggregate Interface Group
- Configure Bonjour Reflector for Network Segmentation
- Use Interface Management Profiles to Restrict Access
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- DHCP Overview
- Firewall as a DHCP Server and Client
- Firewall as a DHCPv6 Client
- DHCP Messages
- Dynamic IPv6 Addressing on the Management Interface
- Configure an Interface as a DHCP Server
- Configure an Interface as a DHCPv4 Client
- Configure an Interface as a DHCPv6 Client with Prefix Delegation
- Configure the Management Interface as a DHCP Client
- Configure the Management Interface for Dynamic IPv6 Address Assignment
- Configure an Interface as a DHCP Relay Agent
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- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
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- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
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- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Create a Source NAT Rule with Persistent DIPP
- PAN-OS
- Strata Cloud Manager
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
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- Network Packet Broker Overview
- How Network Packet Broker Works
- Prepare to Deploy Network Packet Broker
- Configure Transparent Bridge Security Chains
- Configure Routed Layer 3 Security Chains
- Network Packet Broker HA Support
- User Interface Changes for Network Packet Broker
- Limitations of Network Packet Broker
- Troubleshoot Network Packet Broker
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- Enable Advanced Routing
- Logical Router Overview
- Configure a Logical Router
- Create a Static Route
- Configure BGP on an Advanced Routing Engine
- Create BGP Routing Profiles
- Create Filters for the Advanced Routing Engine
- Configure OSPFv2 on an Advanced Routing Engine
- Create OSPF Routing Profiles
- Configure OSPFv3 on an Advanced Routing Engine
- Create OSPFv3 Routing Profiles
- Configure RIPv2 on an Advanced Routing Engine
- Create RIPv2 Routing Profiles
- Create BFD Profiles
- Configure IPv4 Multicast
- Configure MSDP
- Create Multicast Routing Profiles
- Create an IPv4 MRoute
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PAN-OS 11.2
- PAN-OS 11.2
- PAN-OS 11.1
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- PAN-OS 9.0 (EoL)
- PAN-OS 8.1 (EoL)
- Cloud Management and AIOps for NGFW
End-of-Life (EoL)
DNS Overview
DNS performs a crucial role in enabling user access
to network resources so that users need not remember IP addresses
and individual computers need not store a huge volume of domain
names mapped to IP addresses. DNS employs a client/server model;
a DNS server resolves a query for a DNS client by looking up the
domain in its cache and if necessary sending queries to other servers
until it can respond to the client with the corresponding IP address.
The DNS structure of domain names is hierarchical; the top-level
domain (TLD) in a domain name can be a generic TLD (gTLD): com,
edu, gov, int, mil, net, or org (gov and mil are for the United
States only) or a country code (ccTLD), such as au (Australia) or
us (United States). ccTLDs are generally reserved for countries
and dependent territories.
A fully qualified domain name (FQDN) includes at a minimum a
host name, a second-level domain, and a TLD to completely specify
the location of the host in the DNS structure. For example, www.paloaltonetworks.com
is an FQDN.
Wherever a Palo Alto Networks firewall uses an FQDN in the user
interface or CLI, the firewall must resolve that FQDN using DNS.
Depending on where the FQDN query originates, the firewall determines
which DNS settings to use to resolve the query.
A DNS record of an FQDN includes a time-to-live (TTL) value,
and by default the firewall refreshes each FQDN in its cache based
on that individual TTL provided the DNS server, as long as the TTL
is greater than or equal to the Minimum FQDN Refresh
Time you configure on the firewall, or the default setting
of 30 seconds if you don’t configure a minimum. Refreshing an FQDN
based on its TTL value is especially helpful for securing access
to cloud platform services, which often require frequent FQDN refreshes
to ensure highly available services. For example, cloud environments
that support autoscaling depend on FQDN resolutions for dynamically
scaling services up and down, and fast resolutions of FQDNs are
critical in such time-sensitive environments.
By configuring a minimum FQDN refresh time, you limit how small
a TTL value the firewall honors. If your IP addresses don’t change
very often you may want to set a higher Minimum FQDN Refresh Time
so that the firewall doesn’t refresh entries unnecessarily. The
firewall uses the higher of the DNS TTL time and the configured
Minimum FQDN Refresh Time.
For example, two FQDNs have the following TTL values. The Minimum
FQDN Refresh Time overrides smaller (faster) TTL values.
TTL | If Minimum FQDN Refresh = 26 | Actual Refresh Time | |
---|---|---|---|
FQDN A | 20 | 26 | |
FQDN B | 30 | 30 |
The FQDN refresh timer starts when the firewall receives a DNS
response from the DNS server or DNS proxy object that is resolving
the FQDN.
Additionally, you can set a stale timeout to
configure how long the firewall continues to use stale (expired)
FQDN resolutions in the event of an unreachable DNS Server. At the
end of the stale timeout period, if the DNS server is still unreachable,
the stale FQDN entries become unresolved (the firewall removes stale
FQDN entries).
The following firewall tasks are related to DNS:
- Configure your firewall with at least one DNS server so it can resolve hostnames. Configure primary and secondary DNS servers or a DNS Proxy object that specifies such servers, as shown in Use Case 1: Firewall Requires DNS Resolution.
- Customize how the firewall handles DNS resolution initiated by Security policy rules, reporting, and management services (such as email, Kerberos, SNMP, syslog, and more) for each virtual system, as shown in Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System.
- Configure the firewall to act as a DNS server for a client, as shown in Use Case 3: Firewall Acts as DNS Proxy Between Client and Server.
- Configure an Anti-Spyware profile to Use DNS Queries to Identify Infected Hosts on the Network.
- Enable Passive DNS Monitoring, which allows the firewall to automatically share domain-to-IP address mappings based on your network traffic with Palo Alto Networks. The Palo Alto Networks threat research team uses this information to gain insight into malware propagation and evasion techniques that abuse the DNS system.
- Enable Evasion Signatures and then enable evasion signatures for threat prevention.
- Configure an Interface as a DHCP Server. This enables the firewall to act as a DHCP Server and sends DNS information to its DHCP clients so the provisioned DHCP clients can reach their respective DNS servers.