Security Fundamentals

298 soru

Soru 81Soru

A network administrator is deploying Layer 2 security controls on a Cisco Catalyst switch. Which two statements accurately describe the operational requirements and default behaviors of DHCP Snooping? (Select two.)

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Cevap: DHCP server messages such as DHCP OFFER and DHCP ACK are dropped when received on untrusted ports.; DHCP snooping must be enabled globally on the switch as well as explicitly enabled for target VLANs.

Cevap

DHCP server response messages (OFFER/ACK) received on untrusted interfaces are dropped, and DHCP snooping requires both global enablement and VLAN-specific configuration.
DHCP snooping categorizes switch interfaces into trusted and untrusted states. By default, all ports are untrusted and drop DHCP server responses (such as OFFER and ACK) to prevent rogue DHCP servers. Additionally, enabling the feature requires both global activation ('ip dhcp snooping') and VLAN-specific activation ('ip dhcp snooping vlan').

Adım Adım Çözüm

1
Determine default port trust behavior for DHCP Snooping.
When DHCP snooping is enabled, all switch interfaces default to an untrusted state. Untrusted ports block incoming DHCP server response messages (OFFER, ACK, LEASEQUERY) to prevent rogue DHCP server attacks.
Restricting server traffic on user-facing access ports is the primary security function of DHCP snooping.
2
Identify mandatory switch configuration steps.
DHCP snooping requires global activation using the 'ip dhcp snooping' command in global configuration mode, as well as enabling the feature on specific VLANs via 'ip dhcp snooping vlan <vlan-id>'.
Both global and VLAN configuration commands are necessary for the switch to begin inspecting DHCP traffic.

Anahtar Kavram

DHCP Snooping Operational Rules and Port Trust Behavior
Soru 82Soru

A network administrator configures switchport port security on a Cisco Catalyst switch access port using the command 'switchport port-security mac-address sticky'. An end device is connected to the port, and the switch dynamically learns its MAC address into the running configuration. The administrator verifies full network connectivity, but does not enter any additional CLI commands before the switch undergoes an unexpected reboot. Which outcome occurs regarding the port security bindings after the switch reboots?

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Cevap: The dynamically learned sticky MAC address is lost, requiring the switch to relearn the address upon new traffic arrival.

Cevap

The dynamically learned sticky MAC address is lost, requiring the switch to relearn the address upon new traffic arrival.
When port security is configured with sticky MAC address learning, the switch automatically converts dynamically learned MAC addresses into sticky secure MAC addresses and places them into the running configuration in volatile RAM. Because the running configuration was not saved to NVRAM prior to the switch reboot, all dynamically added sticky MAC entries are erased, requiring the switch to relearn host MAC addresses once traffic resumes.

Adım Adım Çözüm

1
Analyze how sticky MAC addresses function in switch memory.
Sticky MAC addresses learned by port security are appended directly to the active running configuration stored in RAM.
The switch dynamic sticky learning feature acts as a shortcut to add static configuration lines into running-config without manual MAC typing.
2
Evaluate the effect of a switch reboot when running configuration has not been saved.
RAM contents are lost during a reboot, reverting the switch to the startup configuration stored in NVRAM.
Without executing 'copy running-config startup-config' or 'write memory', any dynamically learned sticky MAC entries are purged.

Anahtar Kavram

Port Security Sticky MAC Persistence
Tahmini Süre:1m 15s
Soru 83Soru

A network technician is reviewing operational characteristics for standard IPv4 Access Control Lists (ACLs) on a Cisco router. Which of the following statements regarding standard IPv4 ACLs are correct? (Select TWO.)

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Cevap: Standard ACLs filter network traffic based strictly on the source IPv4 address.; Standard ACLs should generally be placed as close to the destination network as possible.

Cevap

Standard IPv4 ACLs filter traffic based only on the source IPv4 address and should be applied as close to the destination as possible to prevent unintentionally blocking traffic intended for other locations.
Standard IPv4 ACLs evaluate packets strictly by their source address. Because they lack the ability to inspect destination addresses or service ports, Cisco best practice is to place standard ACLs as close to the destination network as possible to avoid dropping legitimate traffic destined for other networks.

Adım Adım Çözüm

1
Identify the packet header fields evaluated by standard IPv4 ACLs.
Standard ACLs inspect only the source IPv4 address of incoming packets.
Standard ACL syntax (numbered 1-99 and 1300-1399) does not permit specifying destination addresses or protocol port numbers.
2
Determine the optimal interface placement for standard IPv4 ACLs.
Place standard ACLs near the destination network.
Filtering strictly by source address near the source router would prevent that host from reaching any other destination network.
3
Verify standard ACL default end behavior.
Recognize the presence of the implicit deny rule.
Cisco IOS automatically appends an invisible deny all statement at the end of every ACL list.

Anahtar Kavram

Standard IPv4 ACL Operational Rules and Recommended Placement
Soru 84Soru

A network engineer completes the configuration of Layer 2 security features on a Cisco Catalyst switch connecting client workstations to an upstream router. After enabling DHCP snooping and Dynamic ARP Inspection (DAI) globally and on VLAN 20, client devices on untrusted access ports fail to obtain IPv4 addresses from the DHCP server, and ARP packets arriving from the default gateway on interface GigabitEthernet0/1 are discarded by DAI. Which two configuration steps are required on interface GigabitEthernet0/1 to resolve these issues? (Select two.)

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Cevap: Configure `ip dhcp snooping trust` on interface GigabitEthernet0/1 to allow incoming DHCP server offer and acknowledgment messages.; Configure `ip arp inspection trust` on interface GigabitEthernet0/1 to bypass DAI validation for incoming ARP traffic from the router.

Cevap

Configure `ip dhcp snooping trust` and `ip arp inspection trust` on interface GigabitEthernet0/1.
When DHCP snooping and DAI are enabled on a VLAN, interfaces default to an untrusted state. Uplink interfaces connected to legitimate DHCP servers and routers must be configured as trusted using `ip dhcp snooping trust` and `ip arp inspection trust` so server replies and gateway ARP messages are permitted.

Adım Adım Çözüm

1
Identify the cause of DHCP packet drops on uplink GigabitEthernet0/1.
By default, all switch interfaces are untrusted when DHCP snooping is enabled, causing the switch to drop incoming DHCP server reply messages (OFFER/ACK). Setting `ip dhcp snooping trust` on GigabitEthernet0/1 permits these responses.
Client ports require an authorized path to receive DHCP leases from the server.
2
Identify the cause of ARP packet drops on uplink GigabitEthernet0/1.
By default, DAI treats all ports as untrusted and intercepts all ARP traffic for validation against the DHCP snooping binding table. Setting `ip arp inspection trust` on GigabitEthernet0/1 bypasses this check for legitimate router ARP messages.
Router ARP packets arriving from the core network might not exist in the local DHCP snooping binding table and will be dropped unless the interface is trusted.

Anahtar Kavram

Layer 2 Security Interface Trust States for DHCP Snooping and DAI
Tahmini Süre:1m 30s
Soru 85Soru

A network engineer hardens an enterprise access switch by enabling DHCP Snooping, Dynamic ARP Inspection (DAI), and Port Security. Host A acquires an IPv4 address dynamically via DHCP on interface GigabitEthernet1/0/5, where Port Security is configured with the `switchport port-security mac-address sticky` command. The engineer executes `write memory` to save the running configuration. Later, the switch experiences a power outage and reboots. DHCP Snooping database persistence was not configured with `ip dhcp snooping database`. Upon bootup, Host A attempts to communicate using its active DHCP lease without re-initiating a DHCP DORA sequence. However, all ARP traffic from Host A is dropped by the switch. What is the root cause of these frame drops?

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Cevap: The DHCP snooping binding table was stored in volatile RAM and cleared upon reboot, leaving Dynamic ARP Inspection with no valid IP-to-MAC binding entry to validate Host A's ARP traffic.

Cevap

The DHCP snooping binding database was stored in volatile RAM and cleared upon reboot, leaving Dynamic ARP Inspection with no valid IP-to-MAC binding entry to validate Host A's ARP traffic.
Dynamic ARP Inspection (DAI) relies directly on the DHCP Snooping binding database to validate ARP requests and responses arriving on untrusted ports. By default, the binding table is kept in volatile RAM. If database persistence is not configured via `ip dhcp snooping database <url>`, a switch reload erases all binding entries. When Host A retains its existing IP assignment without issuing a new DHCP request after the switch reboots, DAI finds no matching IP-to-MAC mapping in the binding table and drops Host A's ARP packets.

Adım Adım Çözüm

1
Analyze the operational dependency between Dynamic ARP Inspection (DAI) and DHCP Snooping.
DAI inspects ARP packets on untrusted ports by matching their source IP and MAC addresses against the active DHCP Snooping binding table.
DAI cannot make forwarding decisions without a valid binding entry or a manually configured ARP ACL.
2
Evaluate the storage location and persistence of the DHCP Snooping database.
By default, the DHCP Snooping binding table is maintained exclusively in volatile system RAM unless `ip dhcp snooping database` is configured with a persistent URL (such as flash or TFTP/FTP).
A switch reload flushes volatile memory, completely erasing all dynamically learned bindings.
3
Correlate post-reboot client behavior with DAI validation logic.
Because Host A did not perform a new DHCP exchange after the reboot, no new entry was written to the restored empty binding table. DAI compared Host A's ARP traffic against the empty table and dropped the frames.
Saving the running configuration with `write memory` preserves CLI settings and sticky MACs, but it does not store dynamic DHCP Snooping binding database entries.

Anahtar Kavram

DAI and DHCP Snooping Database Persistence
Soru 86Soru

A network administrator configures an inbound IPv4 extended Access Control List (ACL) on interface GigabitEthernet0/0 to control traffic originating from the engineering subnet 10.50.10.0/2410.50.10.0/24. The objective is to allow HTTP and HTTPS access to an internal web server at 172.16.1.100172.16.1.100, while continuing to allow normal network traffic to all other destinations.

The administrator applies the following configuration:

text
ip access-list extended FILTER_ENGINEERING
permit tcp 10.50.10.0 0.0.0.255 host 172.16.1.100 eq 80
permit tcp 10.50.10.0 0.0.0.255 host 172.16.1.100 eq 443

After applying this ACL to GigabitEthernet0/0 inbound, users in the 10.50.10.0/2410.50.10.0/24 subnet report that while they can access the web server, all access to internet services, DNS, and local file servers is completely blocked. What is the primary cause of this issue?

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Cevap: The ACL does not include a statement to permit remaining traffic, causing all other traffic from the subnet to be dropped by the implicit deny clause at the end of the ACL.

Cevap

The ACL lacks an explicit permit statement for other traffic, causing all unlisted network traffic from the subnet to be dropped by the implicit deny clause at the end of the ACL.
Every IPv4 Access Control List in Cisco IOS contains an implicit 'deny ip any any' statement at the end of the rule list. When creating an ACL intended to selectively allow specific services while permitting general network access, an explicit permit statement (such as 'permit ip 10.50.10.0 0.0.0.255 any') must be placed at the end of the list. Without it, all traffic not explicitly permitted is blocked.

Adım Adım Çözüm

1
Analyze top-down processing of the ACL statements
Matches TCP port 80 traffic to 172.16.1.100 and permits it; matches TCP port 443 traffic to 172.16.1.100 and permits it.
Cisco ACLs process packets sequentially from top to bottom until a match occurs.
2
Evaluate handling of non-web traffic or traffic destined to other IP addresses
Traffic to other services (such as DNS on UDP port 53 or ICMP) does not match the first two permit statements.
Traffic that fails to match any explicit statement falls through to the end of the ACL.
3
Identify the final default behavior of Cisco ACLs
The implicit 'deny ip any any' at the end of the ACL drops all remaining packets.
Every Cisco IOS ACL has an unwritten implicit deny clause at the end. To allow other traffic, an explicit 'permit ip 10.50.10.0 0.0.0.255 any' or similar statement must be appended.

Anahtar Kavram

Implicit Deny Clause in IPv4 ACLs
Tahmini Süre:1m 30s
Soru 87Soru

A network engineer is analyzing connectivity failures on a Cisco Catalyst switch serving VLAN 20. DHCP Snooping and Dynamic ARP Inspection (DAI) are globally enabled and configured on VLAN 20. Users connected to access ports report that they fail to receive DHCP IP addresses, valid ARP requests from hosts are dropped by the switch engine, and port-security sticky MAC addresses learned on access port GigabitEthernet0/2 were lost following a switch reboot.

Which TWO administrative actions are required to resolve the DHCP/DAI packet drops and permanently persist the learned sticky MAC addresses across switch reboots? (Select TWO.)

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Cevap: Configure `ip dhcp snooping trust` and `ip arp inspection trust` on trunk interface GigabitEthernet0/1 connected to the DHCP server and default gateway.; Execute `copy running-config startup-config` after sticky MAC addresses have been dynamically learned into the running configuration.

Cevap

The administrator must trust the uplink trunk port for both DHCP Snooping and Dynamic ARP Inspection, and save the running configuration to the startup configuration so dynamically learned sticky MAC addresses persist across reboots.
Configuring trust settings (`ip dhcp snooping trust` and `ip arp inspection trust`) on the uplink interface allows authorized DHCP responses and ARP packets from the default gateway to pass without being dropped. Additionally, executing `copy running-config startup-config` saves the dynamically learned sticky MAC addresses from RAM into NVRAM, ensuring they persist after a switch reload.

Adım Adım Çözüm

1
Identify the cause of DHCP and ARP drops on the uplink trunk interface.
By default, all switch ports are untrusted when DHCP Snooping and DAI are enabled. Untrusted ports block incoming DHCP server responses (OFFER/ACK) and inspect all ARP packets against the DHCP snooping binding database. Because the gateway router ARP responses and DHCP offer packets arrive on untrusted uplink GigabitEthernet0/1, the switch drops them.
Uplink ports connected to authorized infrastructure (DHCP server, default gateway router) must be designated as trusted using `ip dhcp snooping trust` and `ip arp inspection trust`.
2
Determine why sticky MAC addresses were lost on GigabitEthernet0/2 after a reload.
Port security sticky MAC addresses are dynamically learned and written directly to the active `running-config` in volatile RAM. They are not automatically copied to NVRAM startup memory.
Executing `copy running-config startup-config` (or `write memory`) is mandatory after sticky MAC addresses are learned to preserve them in NVRAM across device reboots.

Anahtar Kavram

Layer 2 Security Trust Boundaries and Configuration Persistence
Soru 88Soru

A network administrator is implementing Layer 2 security controls on a Cisco Catalyst access switch to defend against rogue DHCP servers, ARP poisoning, and unauthorized MAC address access. Match each Layer 2 security configuration command or feature component on the left to its corresponding operational behavior on the right.

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Öğeler

DHCP Snooping Binding Database
switchport port-security violation restrict
ip arp inspection validate src-mac
ip dhcp snooping trust

Eşleşmeler

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Cevap

DHCP Snooping Binding Database matches storing dynamically learned client MAC-to-IP bindings from untrusted interfaces to validate DHCP and ARP traffic. 'switchport port-security violation restrict' matches dropping unauthorized frames, incrementing the violation counter, and sending syslog alerts without shutting down the interface. 'ip arp inspection validate src-mac' matches checking that the Ethernet header source MAC matches the ARP payload sender MAC. 'ip dhcp snooping trust' matches designating an interface allowed to receive DHCP server responses like DHCP OFFER and ACK.
The correct pairings align each command or component to its exact technical operation under Cisco IOS Layer 2 security. DHCP Snooping Binding Database stores client MAC-to-IP mappings. Restrict mode drops offending traffic while logging alerts. DAI src-mac validation compares Ethernet header MAC with ARP payload MAC. Interface DHCP snooping trust allows server messages through uplink ports.

Adım Adım Çözüm

1
Analyze DHCP Snooping Database role
Identify that the binding database stores client IP, MAC, VLAN, and port mapping collected from untrusted ports during DHCP transactions.
This database serves as the authoritative source for validating future IP traffic and ARP inspection requests.
2
Evaluate Port Security Restrict mode behavior
Differentiate restrict mode from protect mode (which drops quietly without logging) and shutdown mode (which disables the port).
Restrict mode drops non-matching MAC frames while generating a log notification and incrementing the violation counter.
3
Examine DAI src-mac validation criteria
Recognize that 'ip arp inspection validate src-mac' explicitly verifies header consistency between Ethernet source MAC and ARP payload sender MAC.
This prevents spoofed MAC attacks where the frame header MAC differs from the internal ARP packet contents.
4
Determine DHCP Snooping Trust configuration requirement
Associate interface-level 'ip dhcp snooping trust' with permitting server-originated messages.
Untrusted ports drop DHCP server packets (OFFER, ACK) by default to prevent rogue DHCP server insertion.

Anahtar Kavram

Layer 2 Security Features (Port Security, DHCP Snooping, DAI)
Soru 89Soru

A network administrator needs to restrict which specific CLI commands an engineer can execute on a router after logging in. Which AAA component is responsible for controlling the specific actions and commands a user is allowed to perform?

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Cevap: Authorization

Cevap

Authorization is the AAA component responsible for specifying permissions and restricting user actions or command execution on a network device.
Authorization is the functional pillar of AAA that determines user rights, privilege levels, and allowable commands after identity has been established.

Adım Adım Çözüm

1
Identify the primary functions of the three pillars of the AAA framework
Authentication proves identity (Who are you?), Authorization grants permissions (What can you do?), and Accounting tracks actions (What did you do?).
Understanding the separation of roles within the AAA framework is essential for network access administration.
2
Match the administrator's requirement to the correct AAA function
Restricting CLI command execution requires privilege and permission enforcement, which falls under Authorization.
Authorization explicitly defines command access levels and privilege levels for an authenticated user.

Anahtar Kavram

AAA Framework Authorization Pillar
Soru 90Soru

A network administrator inspects a Cisco IOS XE switch and finds the following running configuration snippet:

text
username secadmin privilege 15 password 0 C1sc0123!
!
line vty 0 4
transport input ssh
login local

The organization's security hardening baseline requires all local database user accounts to store credentials using PBKDF2 (Type 8) password hashing rather than unencrypted plaintext (Type 0). Which global configuration command correctly updates the local user credential to meet this security standard?

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Cevap: username secadmin privilege 15 secret algorithm-type sha256 C1sc0123!

Cevap

The correct command is 'username secadmin privilege 15 secret algorithm-type sha256 C1sc0123!'.
The command 'username secadmin privilege 15 secret algorithm-type sha256 C1sc0123!' properly replaces the Type 0 unencrypted local password entry with a secure PBKDF2 SHA-256 (Type 8) hash for the specified local user account.

Adım Adım Çözüm

1
Analyze the existing local user configuration statement
The command 'username secadmin privilege 15 password 0 C1sc0123!' uses the 'password 0' syntax, storing the credential as cleartext (Type 0).
Cleartext passwords expose administrative credentials to unauthorized viewing in running configuration files and backups.
2
Identify the Cisco IOS XE command keyword for Type 8 PBKDF2 password hashing
Using 'secret algorithm-type sha256' configures Cisco IOS XE to hash the local user password with SHA-256 based PBKDF2 (Type 8).
The 'secret' keyword replaces weak password storage methods with modern, key-stretching cryptographic algorithms.
3
Formulate the correct global configuration mode command for the specified local user account
'username secadmin privilege 15 secret algorithm-type sha256 C1sc0123!' preserves the username and privilege level while enforcing Type 8 security.
This matches all baseline security requirements specified in the scenario.

Anahtar Kavram

Cisco IOS Local Password Hashing Types and Command Syntax
Soru 91Soru

A network engineer is configuring Layer 2 security controls on access switches to protect against man-in-the-middle attacks and rogue server deployments. Which two statements accurately describe the operational behaviors of DHCP Snooping and Dynamic ARP Inspection (DAI)? (Select two.)

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Cevap: By default, switch interfaces are in an untrusted state for both features, requiring incoming traffic on access ports to be validated against the binding database.; Dynamic ARP Inspection intercepts, logs, and discards ARP packets on untrusted ports that fail IP-to-MAC binding verification.

Cevap

Switch interfaces default to an untrusted state for both features requiring binding database validation, and Dynamic ARP Inspection intercepts and drops invalid ARP packets received on untrusted ports.
Both DHCP Snooping and Dynamic ARP Inspection default all switch ports to an untrusted state, ensuring that unverified DHCP server messages and invalid ARP packets on access ports are intercepted and validated against the binding database. When DAI processes incoming ARP requests or responses on an untrusted port, it compares the packet's IP and MAC address pairing with the database, dropping any packets that do not match.

Adım Adım Çözüm

1
Analyze default port trust state for Layer 2 security features
Confirm that interfaces default to untrusted for both DHCP Snooping and Dynamic ARP Inspection (DAI).
Defaulting access interfaces to untrusted ensures that unauthorized DHCP responses and unverified ARP packets are inspected.
2
Evaluate Dynamic ARP Inspection (DAI) packet processing logic
Identify that DAI intercepts ARP packets on untrusted ports and validates the IP-to-MAC binding.
Packets with invalid or missing bindings in the DHCP snooping table are dropped to prevent ARP poisoning.
3
Evaluate distractor statements regarding configuration persistence and trunking
Rule out non-persistent sticky MAC behavior and unrelated native VLAN mismatch claims.
Sticky MAC addresses reside in volatile RAM running-config until saved, and DAI does not fix native VLAN mismatch errors.

Anahtar Kavram

Layer 2 Security Port Trust States and DAI Binding Validation
Soru 92Soru

Match each AAA framework operational characteristic or protocol mechanism on the left to its corresponding protocol or architectural implementation on the right.

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Öğeler

TACACS+ Authorization Mechanics
RADIUS Accounting Architecture
TACACS+ Packet Security Architecture
RADIUS Authentication & Authorization Coupling

Eşleşmeler

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Cevap

TACACS+ Authorization Mechanics pairs with discrete command verification per transaction over TCP; RADIUS Accounting Architecture pairs with separate UDP transport streams (port 1813/1646); TACACS+ Packet Security Architecture pairs with encrypting the entire payload body over TCP port 49; RADIUS Authentication & Authorization Coupling pairs with combining access-request and response attribute-value pairs while encrypting only the password field over UDP port 1812.
TACACS+ provides full-payload encryption over TCP port 49 and separates AAA pillars, enabling discrete per-command authorization checks. RADIUS couples authentication and authorization into single Access-Request/Accept exchanges over UDP port 1812 (encrypting only the password attribute) and utilizes separate UDP port streams (port 1813) for accounting.

Adım Adım Çözüm

1
Analyze transport protocols and functional separation differences between TACACS+ and RADIUS.
TACACS+ relies on reliable connection-oriented TCP (port 49) and separates AAA functions completely. RADIUS relies on connectionless UDP (ports 1812/1813 or 1645/1646) and combines authentication with authorization.
Understanding transport layer and structural coupling determines how requests are framed.
2
Evaluate encryption scope differences across packet payloads.
TACACS+ encrypts the entire payload body of the packet following the TACACS+ header. RADIUS obfuscates only the User-Password attribute using an MD5-based mechanism, leaving username and other attributes in plaintext.
This key security distinction defines how sensitive payload administrative data is protected in transit.
3
Map command-level authorization and transaction flow.
Because TACACS+ isolates authorization from authentication, a network device can send an authorization request for every command entered at the CLI prompt. RADIUS delivers user profile authorization attributes back during the initial access granting phase.
TACACS+ is optimized for device administration due to per-command granularity.

Anahtar Kavram

AAA Protocol Architecture: TACACS+ vs RADIUS mechanics, transport protocols, functional coupling, and payload encryption scope.
Soru 93Soru

A network technician needs to harden local console line access on a Cisco IOS XE switch using the local user database. Arrange the following Cisco IOS CLI commands in the correct sequential order required to perform this configuration, starting from Privileged EXEC mode (`Switch#`).

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Cevap

The correct command sequence begins with entering global configuration mode (`configure terminal`), creating the local user account (`username admin algorithm-type scrypt secret C1scoPass123!`), accessing the line console context (`line console 0`), enforcing local authentication (`login local`), and exiting line configuration mode (`exit`).
Configuring local user access requires navigating hierarchy levels in Cisco IOS. Starting from `Switch#`, the administrator enters global configuration mode using `configure terminal`. Next, creating the local account with `username ... secret ...` populates the local user database. The technician then transitions into line configuration mode with `line console 0` and binds authentication to the local database using `login local`. Finally, issuing `exit` leaves line configuration mode.

Adım Adım Çözüm

1
Transition from Privileged EXEC mode to Global Configuration mode.
Prompt changes to `Switch(config)#`.
Global configuration commands cannot be executed directly from Privileged EXEC mode.
2
Create the local administrator user account using `username admin algorithm-type scrypt secret C1scoPass123!`.
Local database account is created with a strong Type 9 encrypted secret.
The local account must exist in the device configuration so local authentication succeeds.
3
Navigate into line console configuration mode using `line console 0`.
Prompt changes to `Switch(config-line)#`.
Line-specific authentication settings must be applied within the line configuration sub-mode.
4
Apply the `login local` command under line console configuration.
Console prompt prompts for a username and password defined in the local database.
By default, console lines may require only a line password or no authentication; `login local` forces local database verification.
5
Execute `exit` from line configuration mode.
Prompt returns to `Switch(config)#`.
Completes line configuration and returns to global configuration mode.

Anahtar Kavram

Local Database Authentication and Line Console Security Configuration
Tahmini Süre:1m 30s
Soru 94Soru

A network administrator is implementing the AAA framework on an enterprise switch to manage access. Match each administrative operational task on the left to its corresponding AAA framework pillar on the right.

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Öğeler

Validating user credentials against a centralized database before granting access
Restricting an authenticated engineer to specific privilege levels and CLI commands
Logging session start times, duration, and executed commands for compliance tracking

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Validating user credentials matches Authentication; Restricting privilege levels and CLI commands matches Authorization; Logging session times and executed commands matches Accounting.
Authentication verifies identity ('who you are'), Authorization determines permissions and command rights ('what you can do'), and Accounting logs user activity and session details ('what you did').

Adım Adım Çözüm

1
Analyze the task of validating user credentials.
Credential validation verifies identity (Who are you?), which is the function of Authentication.
Authentication is the first pillar of AAA responsible for verifying identity.
2
Analyze the task of restricting privilege levels and CLI commands.
Restricting access and capabilities enforces permission rules (What can you do?), which is the function of Authorization.
Authorization determines the scope of actions granted to an authenticated identity.
3
Analyze the task of logging session details and command history.
Logging activities creates an audit trail (What did you do?), which is the function of Accounting.
Accounting measures resource consumption and records session event logs.

Anahtar Kavram

Core Pillars of the AAA Framework (Authentication, Authorization, Accounting)
Tahmini Süre:45s
Soru 95Soru

An enterprise network security team is designing an access control architecture for two distinct use cases: granular CLI command authorization with full packet encryption for network engineers managing infrastructure devices via SSH, and port-based 802.1X authentication for wireless clients where authentication and authorization must be evaluated together in a single protocol transaction. Which protocol deployment strategy correctly fulfills both technical requirements based on their underlying operational characteristics?

Cevabı ve açıklamayı göster

Cevap: Deploy TACACS+ over TCP port 49 for infrastructure management because it encrypts the entire packet body and separates AAA functions; deploy RADIUS over UDP ports 1812 and 1813 for 802.1X access control because it encrypts only the password field and combines authentication with authorization.

Cevap

Deploy TACACS+ over TCP port 49 for infrastructure management because it encrypts the entire packet body and separates AAA functions; deploy RADIUS over UDP ports 1812 and 1813 for 802.1X access control because it encrypts only the password field and combines authentication with authorization.
The correct strategy specifies TACACS+ over TCP port 49 for infrastructure management and RADIUS over UDP ports 1812/1813 for 802.1X network access control. TACACS+ encrypts the entire packet payload and decouples the AAA pillars, making it ideal for command-level authorization during SSH administration sessions. RADIUS encrypts only the user password field and combines authentication and authorization into single Access-Accept messages, making it the industry standard for 802.1X client authentication.

Adım Adım Çözüm

1
Analyze device administration requirements
Device management requires per-command authorization and payload encryption for sensitive CLI interactions.
TACACS+ runs on TCP port 49, encrypts the entire packet body (providing confidentiality for command parameters), and strictly separates Authentication, Authorization, and Accounting, allowing dynamic per-command authorization checks.
2
Analyze 802.1X network access control requirements
Network access control requires combined authentication and authorization decisions for endpoint network admission.
RADIUS operates over UDP ports 1812 (authentication/authorization) and 1813 (accounting). It combines authentication and authorization into single Access-Request and Access-Accept/Reject transactions, while encrypting only the password attribute in the header.
3
Synthesize protocol selection
TACACS+ satisfies device administration; RADIUS satisfies 802.1X access control.
Matching TACACS+ (TCP 49, full encryption, modular AAA) with RADIUS (UDP 1812/1813, password-only encryption, coupled auth/assoc) fulfills all design criteria.

Anahtar Kavram

TACACS+ vs RADIUS Protocol Architecture and Operational Differences
Soru 96Soru

A network engineer enables Dynamic ARP Inspection (DAI) on VLAN 20 of a Cisco Catalyst switch where DHCP Snooping is also active. All access interfaces on VLAN 20 are left in the default untrusted state. A critical host connected to interface GigabitEthernet1/0/12 is configured with a static IP address (192.168.20.50/24192.168.20.50/24) and MAC address (0050.56a1.23bc0050.56a1.23bc). Consequently, DAI drops all ARP requests sent by this host because no entry exists for it in the DHCP snooping binding database. The engineer must allow this host to communicate while keeping GigabitEthernet1/0/12 untrusted and maintaining DAI protection on VLAN 20. Which command sequence must be configured on the switch to resolve this issue?

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Cevap: Define an ARP ACL using 'arp access-list STATIC_HOST', permit IP 192.168.20.50 and MAC 0050.56a1.23bc, and apply it with 'ip arp inspection filter STATIC_HOST vlan 20'.

Cevap

Configure an ARP access list matching the static IP and MAC addresses ('arp access-list STATIC_HOST' followed by 'permit ip host 192.168.20.50 mac host 0050.56a1.23bc') and bind it to DAI on the VLAN using 'ip arp inspection filter STATIC_HOST vlan 20'.
Dynamic ARP Inspection (DAI) validates ARP requests and responses on untrusted ports against the DHCP snooping binding database. Because hosts with static IP configurations do not request IP addresses via DHCP, their IP-to-MAC mappings do not exist in the snooping database. To support static hosts without configuring the port as trusted (which would disable DAI checks entirely on that interface), an ARP access list (ARP ACL) must be configured with the host IP and MAC address, then applied to the VLAN using the 'ip arp inspection filter' command.

Adım Adım Çözüm

1
Analyze the cause of packet drops under Dynamic ARP Inspection (DAI).
DAI inspects ARP packets on untrusted ports against the DHCP snooping binding database. Statically addressed hosts do not generate DHCP requests, so they lack database entries and their ARP traffic is dropped.
Untrusted ports undergo mandatory IP-to-MAC binding verification by DAI.
2
Identify the Cisco IOS mechanism for bypassing DHCP snooping database checks for static hosts while preserving DAI.
Configuring an ARP ACL allows administrators to manually define static IP-to-MAC bindings.
DAI evaluates configured ARP ACLs first before falling back to the DHCP snooping binding database.
3
Apply the ARP ACL to the targeted VLAN.
The command 'ip arp inspection filter <acl-name> vlan <vlan-id>' explicitly permits the static host ARP traffic on untrusted ports.
This maintains port untrusted security status for all other hosts while granting an exception for the static host.

Anahtar Kavram

Dynamic ARP Inspection (DAI) ARP ACL Integration for Statically Configured Hosts
Tahmini Süre:2m 0s
Soru 97Soru

A network administrator reviews a Cisco IOS XE router configuration and notices the following line in the running configuration:

`username netadmin privilege 15 password 7 08221509421E05150C`

This entry was created after a technician executed `username netadmin privilege 15 password 0 SecretPass123` followed by `service password-encryption`.

Which statement accurately describes the primary security risk of using this password storage method compared to configuring `username netadmin secret SecretPass123`?

Cevabı ve açıklamayı göster

Cevap: The Type 7 algorithm uses weak vigenère-based obfuscation that can be easily reversed to plain text using standard tools.

Cevap

The Type 7 algorithm uses weak vigenère-based obfuscation that can be easily reversed to plain text using standard tools.
The statement identifying Type 7 as a weak, reversible algorithm is correct. In Cisco IOS, using the `password` command combined with `service password-encryption` produces a Type 7 obfuscated password string. Type 7 uses a simple vigenère-style cipher designed purely to prevent shoulder surfing. It is easily reversible back to plain text. To secure local credentials, administrators should use the `username <name> secret <password>` command, which uses secure one-way hash algorithms (Type 5, Type 8, or Type 9).

Adım Adım Çözüm

1
Analyze the password syntax used in the configuration command
The command `username netadmin password 0 SecretPass123` creates a local database account using plain text (Type 0).
The `password` keyword in Cisco IOS specifies unhashed or weak password storage unless superseded by `secret`.
2
Evaluate the effect of `service password-encryption`
It converts plain text passwords into Type 7 obfuscated strings in the configuration file.
Type 7 encryption uses a well-known, simple reversible cipher intended solely to protect against visual inspection over an admin's shoulder.
3
Compare Type 7 password storage with the `secret` keyword
The `secret` keyword applies strong one-way cryptographic hashing (Type 5 MD5, Type 8 PBKDF2 SHA-256, or Type 9 scrypt), which cannot be reversed back to plain text.
Hardening Cisco IOS device access requires non-reversible hashing algorithms rather than reversible Type 7 obfuscation.

Anahtar Kavram

Local Password Hashing vs Type 7 Obfuscation in Cisco IOS
Soru 98Soru

A network administrator is implementing Layer 2 security controls on Cisco Catalyst access switches. Match each Layer 2 security feature mechanism on the left to its corresponding operational behavior on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

DHCP Snooping Option 82 Insertion
Dynamic ARP Inspection (DAI)
Port Security Sticky MAC Learning
Port Security Restrict Violation Mode

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

DHCP Snooping Option 82 Insertion attaches relay agent information to DHCP requests on untrusted ports. Dynamic ARP Inspection (DAI) intercepts and checks ARP requests against the DHCP binding database on untrusted interfaces. Port Security Sticky MAC Learning dynamically converts learned MAC addresses into running configuration entries. Port Security Restrict Violation Mode drops unauthorized frames, increments the violation counter, and sends a Syslog message without shutting down the interface.
Each feature is paired with its precise Layer 2 operational behavior. DHCP Snooping Option 82 inserts circuit details into client requests. DAI mitigates ARP poisoning by cross-referencing ARP headers against the DHCP snooping database. Sticky MAC converts dynamic address learning into explicit running-configuration statements. Restrict mode drops offending frames and logs an alert while preserving link availability.

Adım Adım Çözüm

1
Analyze DHCP Snooping Option 82 mechanism
Identified that Option 82 adds relay agent metadata (such as switch chassis ID and port interface ID) to client requests on untrusted ports.
Option 82 provides location information to help DHCP servers assign IP addresses and policy parameters.
2
Analyze Dynamic ARP Inspection (DAI) verification mechanism
Determined that DAI validates incoming ARP packets against IP-to-MAC mappings stored in the DHCP snooping binding table.
DAI prevents ARP spoofing and poisoning by dropping invalid ARP packets on untrusted ports.
3
Examine Port Security sticky MAC functionality
Confirmed that sticky MAC dynamically discovers connected devices and writes them to running-config as static MAC entries.
Sticky MAC saves administrators from manually entering host MAC addresses while enforcing access restrictions.
4
Differentiate Port Security violation modes (protect vs restrict vs shutdown)
Matched restrict mode to dropping frames, logging Syslog messages, and incrementing violation counters without err-disabling the interface.
Protect mode drops frames silently without logging, whereas shutdown mode disables the interface entirely.

Anahtar Kavram

Layer 2 Security Mechanisms and Operational Characteristics
Soru 99Soru

A network security engineer analyzes packet traces captured during remote access sessions to network infrastructure and 802.1X wireless client authentications. Which TWO statements correctly describe the architectural and packet-level differences between TACACS+ and RADIUS operations?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: TACACS+ separates authentication and authorization into independent transaction pairs, whereas RADIUS combines authentication and authorization within its access-request and access-accept exchanges.; TACACS+ uses TCP port 49 to ensure reliable transport for fine-grained command-by-command authorization, whereas RADIUS relies on UDP ports 1812 and 1813 for authentication and accounting traffic.

Cevap

The correct statements state that TACACS+ separates authentication and authorization into independent transactions while RADIUS combines them, and that TACACS+ operates over TCP port 49 while RADIUS uses UDP ports 1812 and 1813.
TACACS+ provides modular separation of authentication and authorization, enabling independent transaction pairs, and runs over TCP port 49 for reliable transmission. RADIUS bundles authentication and authorization together within single Access-Request/Accept exchanges and operates over UDP ports 1812 and 1813.

Adım Adım Çözüm

1
Analyze protocol architectural modularity for AAA functions.
Identify that TACACS+ decouples Authentication, Authorization, and Accounting into separate protocol flows, whereas RADIUS combines Authentication and Authorization into a unified Access-Request/Access-Accept exchange.
Modular functional separation allows granular per-command authorization in TACACS+.
2
Evaluate transport layer protocols and port assignments.
Confirm TACACS+ utilizes connection-oriented TCP over port 49, whereas RADIUS utilizes connectionless UDP ports 1812 (Authentication/Authorization) and 1813 (Accounting).
TCP provides session reliability required for administrative control, while UDP minimizes overhead for network access control.
3
Evaluate packet payload encryption mechanisms to reject false statements.
Recognize that TACACS+ encrypts the entire packet payload (excluding the header), while RADIUS encrypts only the password attribute in the Access-Request packet.
Misidentifying payload encryption scope is a common protocol confusion.

Anahtar Kavram

Operational and protocol mechanics distinguishing TACACS+ and RADIUS within the AAA framework.
Soru 100Soru

An inbound IPv4 extended Access Control List (ACL) named SECURE_IN is applied to interface GigabitEthernet0/1 on a Cisco router with the following configuration:

ip access-list extended SECURE_IN
10 permit tcp 172.16.10.0 0.0.0.255 host 192.168.1.100 eq 80
20 permit tcp host 172.16.10.15 192.168.1.0 0.0.0.255 eq 22
30 permit ip host 172.16.10.20 192.168.1.0 0.0.0.255

A host with IPv4 address 172.16.10.15172.16.10.15 sends a packet destined for 192.168.1.100192.168.1.100 targeting TCP port 443 (HTTPS). What action will the router take when processing this packet?

Cevabı ve açıklamayı göster

Cevap: The router drops the packet because it fails to match any explicit permit statement and is caught by the implicit deny clause.

Cevap

The router drops the packet because it fails to match any explicit permit statement and is caught by the implicit deny clause.
Extended ACLs are processed sequentially from top to bottom. Each rule requires matching all specified criteria, including source/destination IP parameters and protocol port numbers. Because the packet on TCP port 443 fails to match lines 10, 20, and 30, it encounters the implicit 'deny ip any any' at the end of the ACL and is dropped.

Adım Adım Çözüm

1
Evaluate line 10 against the incoming packet parameters.
Line 10 permits TCP traffic from 172.16.10.0/24 to host 192.168.1.100 on port 80. The packet uses port 443, so line 10 does not match.
Extended ACLs require all specified layer 3 and layer 4 conditions to match.
2
Evaluate line 20 against the incoming packet parameters.
Line 20 permits TCP traffic from host 172.16.10.15 to subnet 192.168.1.0/24 on port 22. The packet uses port 443, so line 20 does not match.
Port 443 (HTTPS) does not match port 22 (SSH).
3
Evaluate line 30 against the incoming packet parameters.
Line 30 permits IP traffic from host 172.16.10.20 to subnet 192.168.1.0/24. The packet source is 172.16.10.15, so line 30 does not match.
The specific source host IP address specified in line 30 does not match 172.16.10.15.
4
Apply the implicit ACL processing behavior at the end of the list.
The packet is dropped.
All Cisco IPv4 ACLs conclude with an unwritten, implicit 'deny ip any any' statement.

Anahtar Kavram

Top-down sequential evaluation of Extended IPv4 ACLs and the implicit deny clause
Tahmini Süre:1m 30s
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