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17.1 Configure IPv4 and IPv6 Addresses

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Red Hat Certified System Administrator RHCSA

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1 Introduction & Exam Overview

1.1 Current Exam Facts 1.2 Lab Setup & Performance-Based Study Strategy

2 Essential Tools: Shell, Redirection & Text Analysis

2.1 Shell Prompt and Command Syntax 2.2 Input-Output Redirection and Pipes 2.3 grep and Regular Expressions for Text Analysis

3 Essential Tools: Remote Access, Users & Text Editing

3.1 Access Remote Systems Using SSH 3.2 Log In and Switch Users in Multiuser Targets 3.3 Create and Edit Text Files

4 Essential Tools: Files, Links & Archives

4.1 Create, Delete, Copy, and Move Files and Directories 4.2 Hard and Soft Links 4.3 Archive and Compress with tar, gzip, and bzip2

5 Essential Tools: Permissions & System Documentation

5.1 List, Set, and Change Standard ugo/rwx Permissions 5.2 System Documentation: man, info, and /usr/share/doc

6 Manage Software: RPM and Flatpak

6.1 Configure Access to RPM Repositories 6.2 Install and Remove RPM Software Packages 6.3 Configure Access to Flatpak Repositories 6.4 Install and Remove Flatpak Software Packages

7 Create Simple Shell Scripts

7.1 Conditional Execution: if, test, and [] 7.2 Looping Constructs for Files and Input 7.3 Process Script Inputs ($1, $2, and Beyond) 7.4 Process Shell Command Output in Scripts

8 Operate Running Systems: Boot and Recovery

8.1 Boot, Reboot, and Shut Down a System Normally 8.2 Boot Systems into Different Targets Manually 8.3 Interrupt the Boot Process to Gain Access

9 Operate Running Systems: Processes and Tuning

9.1 Identify and Kill CPU/Memory Intensive Processes 9.2 Adjust Process Scheduling 9.3 Manage Tuning Profiles

10 Operate Running Systems: Logs, Services & File Transfer

10.1 Locate and Interpret System Log Files and Journals 10.2 Preserve System Journals 10.3 Start, Stop, and Check Status of Network Services 10.4 Securely Transfer Files Between Systems

11 Configure Local Storage: Partitions and LVM

11.1 List, Create, and Delete Partitions on GPT Disks 11.2 Create and Remove Physical Volumes 11.3 Assign Physical Volumes to Volume Groups 11.4 Create and Delete Logical Volumes

12 Configure Local Storage: Mounting and Expansion

12.1 Mount File Systems at Boot by UUID or Label 12.2 Add Partitions, Logical Volumes, and Swap Non-Destructively

13 Create and Configure File Systems: Local FS and Permissions

13.1 Create, Mount, and Use VFAT, ext4, and XFS File Systems 13.2 Extend Existing Logical Volumes 13.3 Diagnose and Correct File Permission Problems

14 Create and Configure File Systems: NFS and autofs

14.1 Mount and Unmount Network File Systems Using NFS 14.2 Configure autofs

15 Deploy and Maintain: Scheduling, Services & Targets

15.1 Schedule Tasks with at, cron, and systemd Timers 15.2 Start, Stop, and Enable Services at Boot 15.3 Configure Systems to Boot into a Specific Target

16 Deploy and Maintain: Time, Software Updates & Bootloader

16.1 Configure Time Service Clients 16.2 Install and Update Software from CDN, Remote Repos, and Local Files 16.3 Modify the System Bootloader

17 Manage Basic Networking

17.1 Configure IPv4 and IPv6 Addresses 17.2 Configure Hostname Resolution 17.3 Configure Network Services to Start Automatically at Boot 17.4 Restrict Network Access Using firewalld and firewall-cmd

18 Manage Users and Groups

18.1 Create, Delete, and Modify Local User Accounts 18.2 Change Passwords and Adjust Password Aging 18.3 Create, Delete, and Modify Local Groups and Memberships 18.4 Configure Privileged Access

19 Manage Security: Firewall, umask & SSH Keys

19.1 Configure Firewall Settings with firewall-cmd and firewalld 19.2 Manage Default File Permissions 19.3 Configure Key-Based Authentication for SSH

20 Manage Security: SELinux Modes and Contexts

20.1 Set Enforcing and Permissive Modes for SELinux 20.2 List and Identify SELinux File and Process Contexts 20.3 Restore Default File Contexts

21 Manage Security: SELinux Ports and Booleans

21.1 Manage SELinux Port Labels 21.2 Use Boolean Settings to Modify SELinux Settings

17.1 Configure IPv4 and IPv6 Addresses

Key Takeaways Explain This Topic AI

On RHEL 10, configure persistent interface addressing primarily with nmcli (or nmtui) against NetworkManager connection profiles—not by hand-editing temporary runtime-only settings.

Use nmcli connection modify (or add) for IPv4/IPv6 method, addresses, gateway, and DNS; apply with nmcli connection up; verify with ip addr, ip route, and nmcli device/connection show.

Static IPv4 uses ipv4.method manual with ipv4.addresses and usually ipv4.gateway; IPv6 uses ipv6.method manual or auto/disabled as the task requires.

ip addr and ip link show live state; they do not by themselves replace a saved NetworkManager profile that must survive reboot.

EX200 success is correct addressing after reboot: connection enabled, profile applied, interface up, and routes/DNS matching the task.

Last updated: August 2026

17.1 Configure IPv4 and IPv6 Addresses

Quick Answer: Prefer NetworkManager with nmcli . Set addresses on a connection profile ( nmcli connection modify or add ), then nmcli connection up . Verify with ip addr , ip route , and nmcli -f all connection show NAME . Runtime-only ip addr add without a saved profile usually fails after reboot.

Official skill and exam framing

Under Manage basic networking , Red Hat expects you to configure IPv4 and IPv6 addresses . Lab wording looks like:

  • “Configure the primary interface with static IPv4 172.25.250.11/24 and gateway 172.25.250.254 .”
  • “Ensure the host has a static IPv6 address 2001:db8:0:1::11/64 .”
  • “Use NetworkManager so the configuration persists across reboot.”

You are graded on end state after reboot : correct address on the right interface (or connection), gateway if required, and a profile NetworkManager will reapply. Memorize tools, not just temporary CLI tricks.

NetworkManager is the RHEL path

On modern RHEL (including RHEL 10), NetworkManager owns interface configuration. Connection profiles store method, addresses, routes, and DNS. Devices (NICs) are bound to profiles.

  • Concept Meaning
  • Device Hardware or virtual NIC ( eth0 , ens192 , enp1s0 )
  • Connection Named profile NetworkManager applies to a device
  • Active connection Profile currently applied systemctl is-active NetworkManager
  • nmcli general status
  • nmcli device status
  • nmcli connection show
  • nmcli connection show --active

If NetworkManager is stopped or disabled, fix that first (see Section 17.3). Do not fight NetworkManager by only editing legacy ifcfg files unless a task forces an unusual path— nmcli is the reliable EX200 skill.

  • Inspect before you change ip link show
  • ip -br addr
  • ip addr show
  • ip route
  • nmcli device show
  • nmcli -f NAME,UUID,TYPE,DEVICE,FILENAME connection show

Identify:

Which device is the exam interface (often the only non- lo NIC, or the one already on the lab network).

Which connection name is bound to it (may match the device name or a friendly name like Wired connection 1 ).

Whether addressing is currently auto (DHCP) or manual . nmcli device show ens192 | egrep 'GENERAL|IP4|IP6|CONNECTION'

nmcli connection show ens192

# or:

nmcli connection show "Wired connection 1"

Tip: Quote connection names that contain spaces.

  • Static IPv4 with nmcli connection modify
  • Assume device ens192 already has connection profile ens192 : sudo nmcli connection modify ens192 \
  • ipv4.method manual \
  • ipv4.addresses 172.25.250.11/24 \
  • ipv4.gateway 172.25.250.254 \
  • ipv4.dns 172.25.250.254 \
  • connection.autoconnect yes

sudo nmcli connection up ens192

  • Property Role
  • ipv4.method manual Static IPv4 (not DHCP)
  • ipv4.addresses Address/prefix ( a.b.c.d/nn )
  • ipv4.gateway Default gateway
  • ipv4.dns DNS servers (space-separated if multiple)
  • ipv4.dns-search Search domains when required
  • connection.autoconnect yes Activate at boot when device is available
  • Multiple addresses on one connection: sudo nmcli connection modify ens192 \
  • ipv4.addresses "172.25.250.11/24,172.25.250.12/24"
  • Or append: sudo nmcli connection modify ens192 +ipv4.addresses 172.25.250.12/24
  • Create a new connection profile

When you need a clean profile or the task says “create a connection”: sudo nmcli connection add type ethernet con-name lab ifname ens192 \

  • ipv4.method manual \
  • ipv4.addresses 172.25.250.11/24 \
  • ipv4.gateway 172.25.250.254 \
  • ipv6.method ignore

sudo nmcli connection up lab

ifname binds the profile to a device. Bring the intended profile up so it becomes active (only one ethernet profile typically active per device).

  • DHCP / automatic IPv4 sudo nmcli connection modify ens192 ipv4.method auto
  • sudo nmcli connection up ens192

auto is NetworkManager’s DHCP (and related automatic) method for IPv4. Use when the task requires dynamic addressing rather than a fixed IP.

IPv6 configuration

  • Method Meaning
  • ipv6.method auto Automatic configuration (SLAAC/DHCPv6 as applicable)
  • ipv6.method manual Static IPv6

ipv6.method disabled / ignore Do not configure IPv6 on this connection (wording varies by NM version; use what nmcli accepts on the exam host)

  • Static IPv6 example: sudo nmcli connection modify ens192 \
  • ipv6.method manual \
  • ipv6.addresses 2001:db8:0:1::11/64 \
  • ipv6.gateway 2001:db8:0:1::1
  • sudo nmcli connection up ens192
  • Combined dual-stack (common exam pattern): sudo nmcli connection modify ens192 \
  • ipv4.method manual \
  • ipv4.addresses 172.25.250.11/24 \
  • ipv4.gateway 172.25.250.254 \
  • ipv6.method manual \
  • ipv6.addresses 2001:db8:0:1::11/64 \
  • ipv6.gateway 2001:db8:0:1::1 \
  • connection.autoconnect yes

sudo nmcli connection up ens192

If the task only mentions IPv4, leave IPv6 as-is unless it conflicts; if it requires IPv6 static, set ipv6.method manual explicitly.

Apply changes: connection up vs device reapply

nmcli connection modify updates the stored profile. Runtime may lag until you re-activate: sudo nmcli connection up ens192

# equivalent idea:

sudo nmcli device reapply ens192 # when supported and profile already active

Prefer connection up after address changes so you know the profile reapplied cleanly. Watch for errors (wrong syntax, address conflict, missing device).

  • Verify with ip and nmcli ip -br addr show ens192
  • ip addr show ens192
  • ip -4 route
  • ip -6 route
  • ping -c 2 172.25.250.254
  • ping -c 2 -6 2001:db8:0:1::1
  • nmcli -f ipv4.method,ipv4.addresses,ipv4.gateway,ipv6.method,ipv6.addresses connection show ens192
  • nmcli device show ens192 | egrep 'IP4.ADDRESS|IP4.GATEWAY|IP6.ADDRESS'

Confirm prefix length ( /24 not forgotten), gateway on the correct subnet, and that the address appears on the correct device .

Runtime ip commands vs persistence # Temporary only — useful for diagnosis, not full EX200 persistence:

  • sudo ip addr add 172.25.250.11/24 dev ens192
  • sudo ip route add default via 172.25.250.254

These change live kernel state. Without a matching NetworkManager (or other persistent) configuration, they disappear on reboot or when NM reapplies a different profile. Use ip to verify and to understand state; use nmcli to configure for the exam . ip link set ens192 up

  • ip link set ens192 down # careful: may cut remote access
  • nmtui (optional UI) sudo nmtui

Text UI: Edit a connection → IPv4/IPv6 Configuration → Manual → addresses/gateway/DNS → OK → Activate a connection. Same persistence model as nmcli. Use if you prefer menus under time pressure, but still verify with ip addr .

Hostname is not an IP address

Setting the system hostname ( hostnamectl ) does not assign IPv4/IPv6. Addressing is this section; name resolution is Section 17.2. Tasks often require both —do not stop after only setting a pretty hostname.

  • Exam workflows
  • Workflow A — Static IPv4 on existing profile nmcli device status
  • nmcli connection show
  • sudo nmcli connection modify ens192 \
  • ipv4.method manual \
  • ipv4.addresses 172.25.250.11/24 \
  • ipv4.gateway 172.25.250.254 \
  • connection.autoconnect yes
  • sudo nmcli connection up ens192
  • ip -br addr show ens192
  • ip route | grep default
  • Workflow B — New named connection sudo nmcli connection add type ethernet con-name static-lab ifname ens192 \
  • ipv4.method manual ipv4.addresses 172.25.250.11/24 \
  • ipv4.gateway 172.25.250.254 ipv6.method ignore
  • sudo nmcli connection up static-lab
  • nmcli connection show --active
  • Workflow C — Static IPv6 only addition sudo nmcli connection modify ens192 \
  • ipv6.method manual \
  • ipv6.addresses 2001:db8:0:1::11/64 \
  • ipv6.gateway 2001:db8:0:1::1
  • sudo nmcli connection up ens192
  • ip -6 addr show ens192
  • Workflow D — Prove persistence mindset nmcli -g connection.autoconnect connection show ens192
  • nmcli -g ipv4.method,ipv4.addresses connection show ens192

# After any allowed reboot in practice:

  • ip -br addr; ip route
  • Common traps

ip addr add only — works now, gone after reboot or NM reapply.

Forgetting ipv4.method manual — leftover auto may fight or ignore your static intent.

Missing prefix — 172.25.250.11 without /24 is incomplete for NM addressing.

Wrong connection name — modifying a profile not bound to the active device.

modify without connection up — disk profile correct, live address stale.

Gateway on wrong subnet — no default route reachability.

Cutting your only remote IP mid-change without console access—change carefully on SSH sessions.

Disabling IPv6 when the task requires an IPv6 address.

Assuming hostname equals DNS or IP configuration.

Leaving autoconnect no so the profile does not return after reboot.

Relationship to other sections

  • Skill Section
  • IPv4/IPv6 addresses 17.1 (this)
  • Hostname, hosts, resolver 17.2
  • NetworkManager at boot 17.3
  • firewalld restrict access 17.4
  • Section checkpoint

You should list devices and connections, set static or automatic IPv4 and IPv6 with nmcli connection modify / add , reapply with nmcli connection up , verify with ip addr and ip route , keep connection.autoconnect yes when the address must return after boot, and treat NetworkManager profiles—not one-off ip commands—as the EX200 source of truth for addressing on RHEL 10.