Tüm alıştırma soruları

2237 soru

Tüm türler2,237 Çoktan seçmeli1,150 Çoklu seçim488 Sayısal30 Eşleştirme350 Sıralama201 Kısa cevap18

Soru 1921Soru →

A network administrator is auditing a wireless network installation across a single-floor office facility operating on the $2.4\text{ GHz}$ spectrum. The audit reveals that three adjacent access points (APs) along a main hallway are configured to use $20\text{ MHz}$ channel widths on channels $1$ , $3$ , and $5$ , respectively. Users connected in this hallway experience frequent frame collisions, high latency, and degraded throughput due to spectral overlap. Which of the following channel assignment adjustments should the administrator make to resolve this interference?

Assign the three access points to channels

1

6

, and

11

, respectively.

Assign the three access points to channels

2

4

, and

6

, respectively.

Increase the channel width on all three access points to

40\text{ MHz}

while retaining channels

1

3

, and

5

Reconfigure the access points to operate on channels

1

5

, and

9

, respectively.

Cevabı ve açıklamayı göster

Cevap: Assign the three access points to channels $1$ , $6$ , and $11$ , respectively.

Cevap

Reconfigure the access points to use channels 1, 6, and 11, respectively, which are the standard non-overlapping channels in the 2.4 GHz band.

In 2.4 GHz Wi-Fi deployments, standard 20 MHz channels require a minimum of 5 channel increments between center frequencies to prevent spectral overlap. Selecting channels 1, 6, and 11 provides complete frequency separation and eliminates adjacent-channel interference.

Adım Adım Çözüm

Analyze the spectral properties of 2.4 GHz Wi-Fi channels.

Each 2.4 GHz channel is spaced 5 MHz apart, but a standard 802.11 20 MHz channel requires a spectral footprint of 20 to 22 MHz.

Adjacent channel assignments such as channels 1, 3, and 5 overlap heavily in frequency space, causing severe adjacent-channel interference (ACI).

Identify non-overlapping channel combinations for the 2.4 GHz band.

Channels 1, 6, and 11 have center frequencies of 2412 MHz, 2437 MHz, and 2462 MHz, providing 25 MHz separation between center frequencies.

This 25 MHz spacing ensures zero spectral overlap between adjacent AP coverage cells when using 20 MHz channel widths.

Anahtar Kavram

2.4 GHz Non-Overlapping Channel Planning

Soru 1922Soru →

A network administrator is assigning static IP addresses to server interfaces within the network block $192.168.100.0/25$ . Which of the following IPv4 addresses are valid, usable host addresses within this subnet? (Select TWO.)

Geçerli olan tümünü seçin

192.168.100.1

192.168.100.126

192.168.100.0

192.168.100.127

Cevabı ve açıklamayı göster

Cevap: $192.168.100.1$ ; $192.168.100.126$

Cevap

The addresses

192.168.100.1

and

192.168.100.126

are the correct usable host IP addresses.

For a CIDR block of

192.168.100.0/25

, the address range spans from

192.168.100.0

through

192.168.100.127

. The network address is

192.168.100.0

and the broadcast address is

192.168.100.127

. Excluding these two reserved addresses leaves the usable host range as

192.168.100.1

through

192.168.100.126

. Both

192.168.100.1

and

192.168.100.126

fall strictly within this usable range.

Adım Adım Çözüm

Determine the total block size and network boundary for CIDR prefix /25.

A /25 prefix provides

2^{32-25} = 2^7 = 128

total IP addresses (

192.168.100.0

192.168.100.127

The CIDR prefix defines the number of host bits (

32 - 25 = 7

bits).

Identify the reserved Network ID and Broadcast address.

The Network ID is

192.168.100.0

(first address) and the Broadcast address is

192.168.100.127

(last address).

The first IP address identifies the network itself and the last IP address is reserved for broadcast traffic within the subnet.

Calculate the range of usable host IP addresses.

Usable host IP range is from

192.168.100.1

192.168.100.126

, yielding

128 - 2 = 126

usable host addresses.

Usable host addresses consist of all IP addresses between the Network ID and the Broadcast address.

Anahtar Kavram

Usable IPv4 Host Range Calculation for Subnets

Tahmini Süre:1m 30s

Soru 1923Soru →

A workstation user attempts to access a web portal at `portal.corp.contoso.com`. The local recursive DNS resolver receives the request with an empty cache. During the lookup, the resolver discovers that `portal.corp.contoso.com` is configured as a CNAME alias pointing to `hosting-node-01.external-provider.net`. What is the correct sequence of steps the recursive DNS resolver takes to resolve the final IP address for the workstation?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The resolution sequence begins by querying the original domain's authoritative DNS server to receive the CNAME alias mapping, extracting the canonical hostname to start a new lookup, querying the canonical domain's authoritative server for its A record, receiving the IPv4 address response, and finally delivering the IP address to the requesting workstation while caching both records.

When resolving a domain configured with a CNAME record, a recursive DNS resolver must follow a multi-stage process. First, it queries the authoritative server for the original domain (`corp.contoso.com`), which returns a CNAME record pointing to an alias target (`hosting-node-01.external-provider.net`). Recognizing that a CNAME provides a canonical hostname rather than an IP address, the resolver starts a new lookup chain for the target hostname. It queries the authoritative server for `external-provider.net` to obtain the A record. Once the target server responds with the IPv4 address, the resolver caches both the intermediate CNAME mapping and the final A record, and finally delivers the IP address back to the workstation stub resolver.

Adım Adım Çözüm

Query initial domain authoritative server

Received CNAME record mapping portal.corp.contoso.com to hosting-node-01.external-provider.net

The resolver must query the domain specified in the original request to identify its record type and mapping.

Process alias and initiate canonical lookup

New name lookup target established for hosting-node-01.external-provider.net

CNAME records do not contain IP addresses; they require an additional resolution path for the target canonical name.

Query canonical domain authoritative server

A record request sent to authoritative DNS server for external-provider.net

Authoritative servers for external-provider.net store the actual host IP mapping for hosting-node-01.

Receive IPv4 address response

Received A record containing the host IP address

Provides the actionable network layer address required to establish network connections.

Cache records and respond to client

Workstation receives the IP address, and resolver stores CNAME and A records in cache

Fulfills the recursive client request and optimizes future name resolution requests via caching.

Anahtar Kavram

DNS Recursive Resolution and CNAME Alias Chaining

Tahmini Süre:1m 30s

Soru 1924Soru →

A network technician provisions a new database server on VLAN 50 ( $10.50.0.0/24$ ). Upon booting up, running `ip addr show` reveals that the host interface has acquired an IP address of $169.254.88.12/16$ . The technician manually assigns a static address of $10.50.0.50/24$ to the interface and verifies that the host can successfully ping its default gateway at $10.50.0.1$ . The centralized DHCP server resides on VLAN 10 ( $10.10.0.5/24$ ).

Which of the following are the MOST likely causes of the host initially receiving an APIPA address? (Select TWO.)

Geçerli olan tümünü seçin

The router interface serving VLAN 50 is missing an IP helper address pointing to the DHCP server at

10.10.0.5

The server's default gateway address was incorrectly set to

10.10.0.5

instead of

10.50.0.1

The centralized DHCP server does not have an active IP scope configured for the

10.50.0.0/24

network segment.

The

10.50.0.0/24

subnet mask on the client blocks Layer 2 broadcast transmission of the initial DHCP DISCOVER frame.

Cevabı ve açıklamayı göster

Cevap: The router interface serving VLAN 50 is missing an IP helper address pointing to the DHCP server at $10.10.0.5$ .; The centralized DHCP server does not have an active IP scope configured for the $10.50.0.0/24$ network segment.

Cevap

The host received an APIPA address because the router interface for VLAN 50 lacks an IP helper address pointing to the remote DHCP server, or the DHCP server lacks an active scope for the 10.50.0.0/24 subnet.

An APIPA address (169.254.x.x) confirms that the client failed to receive a response from a DHCP server. Since static IP configuration proves local VLAN 50 Layer 2 and Layer 3 connectivity to the default gateway is operational, the failure stems from cross-VLAN DHCP transport or pool availability. First, routers block broadcast traffic by default; thus, the router interface on VLAN 50 must have an IP helper address configured to forward DHCP broadcasts as unicast traffic to the DHCP server on VLAN 10. Second, the DHCP server must have an active address scope for the 10.50.0.0/24 network segment to lease addresses to clients on that relay pool.

Adım Adım Çözüm

Analyze the client IP address symptom

The host obtained 169.254.88.12/16, which is an APIPA address indicating that the client sent DHCP DISCOVER frames but never received a valid DHCP OFFER/ACK.

Identifying APIPA establishes that DHCP negotiation failed completely rather than succeeding with bad option settings.

Evaluate local Layer 2 connectivity

Static configuration of 10.50.0.50/24 successfully pings the gateway at 10.50.0.1.

This rules out physical cable failure, switch port VLAN misassignment, or default gateway interface shutdown.

Diagnose cross-subnet DHCP forwarding and scope availability

Because the DHCP server is located on VLAN 10 (10.10.0.5) while the host is on VLAN 50 (10.50.0.0/24), the router interface for VLAN 50 must act as a DHCP relay agent using `ip helper-address 10.10.0.5`. Furthermore, the DHCP server must hold an active pool matching the 10.50.0.0/24 network.

Without the relay agent, broadcast DISCOVER messages cannot cross Layer 3 boundaries. Without an active scope, the server cannot offer an address for that subnet.

Anahtar Kavram

DHCP Relay and Scope Configuration in Multi-VLAN Environments

Soru 1925Soru →

A system administrator is troubleshooting an inability to establish a secure remote administration session via SSH to a Linux server located at $192.168.1.50$ . The administrator executes the command `netstat -an` directly on the server to inspect active network socket states and receives the following truncated output:

Proto Local Address Foreign Address State
TCP 0.0.0.0:23 0.0.0.0:0 LISTENING
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING
TCP 0.0.0.0:443 0.0.0.0:0 LISTENING

Based on the utility output, which condition explains why remote SSH connections to this server are failing?

The SSH daemon is not running or is not bound to listen on standard TCP port 22.

The server is currently accepting SSH sessions on TCP port 23, indicating an active encrypted remote management service.

The command output demonstrates that local DNS client resolution has failed to map numerical socket addresses to human-readable hostnames.

The listening sockets indicate that an AAAA DNS resource record is missing for IPv4 interface binding.

Cevabı ve açıklamayı göster

Cevap: The SSH daemon is not running or is not bound to listen on standard TCP port 22.

Cevap

The SSH daemon is not running or is not bound to listen on standard TCP port 22.

Secure Shell (SSH) operates over TCP port 22 by default. In the provided `netstat -an` output, the server lists active listening services on TCP ports 23 (Telnet), 80 (HTTP), and 443 (HTTPS), but TCP port 22 is completely missing. This indicates the SSH daemon process is not running or is not listening on its default port, causing incoming connection attempts to fail.

Adım Adım Çözüm

Analyze the utility and parameters used

The `netstat -an` command displays all active network connections and listening ports (`-a`) using numerical IP addresses and port numbers (`-n`).

Numerical display prevents DNS lookup delays and shows exact port numbers being monitored.

Inspect listening TCP ports in the command output

The server has active listeners on TCP port 23 (Telnet), TCP port 80 (HTTP), and TCP port 443 (HTTPS).

To accept incoming connections for a protocol, a service daemon must be bound and listening on its designated port.

Evaluate incoming connection request requirements against active listeners

SSH relies on TCP port 22 by default. Since port 22 is absent from the LISTENING socket table, incoming SSH connection requests will be rejected by the TCP stack.

The SSH service process is either stopped or configured to use a non-standard port not shown in the listening table.

Anahtar Kavram

Port and protocol monitoring using netstat/ss utilities

Tahmini Süre:1m 30s

Soru 1926Soru →

A network technician is investigating a report that a Windows client workstation cannot load an internal intranet application hosted on a distant subnet (`172.16.10.50`). The technician decides to perform a bottom-up command-line diagnostic workflow to isolate the point of failure. In what sequence should the technician execute the following commands to logically isolate the issue from local IP configuration to remote network path routing?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct troubleshooting sequence is: 1) `ipconfig /all` to inspect local IP settings, 2) `ping 127.0.0.1` to test the internal TCP/IP stack, 3) `ping 192.168.1.1` to verify default gateway reachability, and 4) `tracert 172.16.10.50` to isolate route failures across remote hops.

A structured bottom-up command-line diagnostic process begins at the local host and moves outward: first inspecting local IP settings (`ipconfig /all`), testing the internal protocol stack (`ping 127.0.0.1`), validating local gateway reachability (`ping 192.168.1.1`), and finally tracing path hops to remote destinations (`tracert`).

Adım Adım Çözüm

Verify local IP configuration using `ipconfig /all`.

Displays client network adapter settings, DHCP status, assigned IP, subnet mask, default gateway, and DNS servers.

Establishes baseline configuration and identifies basic issues like missing default gateways or APIPA address assignments.

Test local TCP/IP stack functionality using `ping 127.0.0.1`.

Receives ICMP echo replies from the local loopback interface.

Confirms the protocol stack and driver software are bound properly to the local adapter.

Test local subnet reachability by pinging the default gateway IP (`192.168.1.1`).

Verifies ARP resolution and ICMP packet transport across the immediate Layer 2 network segment.

Ensures the workstation can successfully transmit packets to its local router interface.

Trace the path to the remote host using `tracert 172.16.10.50`.

Displays hop-by-hop latency and identifies the specific router interface where packets are dropped.

Isolates inter-subnet routing or firewall policy failures further along the path beyond the local gateway.

Anahtar Kavram

Standard Command-Line Bottom-Up Network Troubleshooting Sequence

Soru 1927Soru →

A network engineering team is executing a disaster recovery failover plan to restore operations at a secondary data center following a catastrophic failure at the primary site. Arrange the recovery actions in the correct sequential order based on standard network and infrastructure service dependencies, from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct order of steps is: 1) Establish foundational layer 2 switching and layer 3 routing infrastructure, 2) Restore core infrastructure and directory services (Active Directory, internal DNS, DHCP), 3) Recover backend database storage volumes and application servers, 4) Perform validation and synthetic testing to verify data integrity, and 5) Update external DNS records and edge gateway routing to cut over client traffic.

Disaster recovery failovers must adhere strictly to infrastructure dependency order. Underlying network switching and routing must be restored first to enable inter-subnet communication. Next, core directory and name resolution services (Active Directory, DNS, DHCP) must be brought online so that subsequent hosts can resolve IP endpoints and authenticate. Once directory services exist, application and database servers can be restored and booted. Comprehensive validation testing is conducted prior to production exposure. Finally, external DNS records and edge routing are updated to direct live client traffic to the recovered site.

Adım Adım Çözüm

Identify physical and network layer prerequisites.

Switching, VLAN trunking, and inter-VLAN routing at the DR site are brought online.

Without active layer 2 and layer 3 networking, host machines cannot perform network communication or reach backup repositories.

Identify core network service dependencies.

Domain controllers, DNS servers, and DHCP relays are restored.

Enterprise applications rely on domain authentication and hostname resolution during startup scripts and database connection strings.

Restore data and application servers.

Database volumes and application virtual machines are recovered from backups.

With directory services online, application workloads can connect to databases and register domain security SIDs.

Verify operational readiness.

Synthetic end-to-end tests are executed internally by network and system admins.

Exposing production users to unvalidated systems risks data corruption or service outages.

Divert live client traffic.

Public DNS A/AAAA/CNAME records and BGP/edge routes are modified.

Traffic cutover must be the final action after confirming all underlying dependencies are operating as expected.

Anahtar Kavram

Disaster Recovery Infrastructure Dependency Sequence

Soru 1928Soru →

A network administrator is troubleshooting an issue where workstations assigned to VLAN 30 on Switch-1 cannot communicate with servers on VLAN 30 attached to Switch-2. An audit of interface GigabitEthernet0/1 on Switch-1 reveals that it was mistakenly configured with static access mode (`switchport mode access`). Additionally, the trunk configuration documentation indicates VLAN 30 must be explicitly allowed, but the interface allowed list is currently restricted to VLANs 10 and 20 (`switchport trunk allowed vlan 10,20`).

Which TWO configuration commands must the administrator execute on Switch-1 interface GigabitEthernet0/1 to establish an 802.1Q trunk link and permit VLAN 30 traffic to pass across it?

Geçerli olan tümünü seçin

switchport mode trunk

switchport trunk allowed vlan add 30

spanning-tree vlan 30 priority 4096

ip address 192.168.30.1 255.255.255.0

Cevabı ve açıklamayı göster

Cevap: switchport mode trunk; switchport trunk allowed vlan add 30

Cevap

The correct commands are 'switchport mode trunk' and 'switchport trunk allowed vlan add 30'.

To establish proper Layer 2 trunking for VLAN 30, the port operational mode must first be changed from access to trunk using the trunk mode command. Secondly, because the trunk has an explicit allowed list restricting traffic, VLAN 30 must be added to the allowed VLAN list on the interface using the add keyword so it does not overwrite current allowed VLANs.

Adım Adım Çözüm

Identify the trunking mode status

The interface is operating in static access mode rather than trunking mode.

An access port strips VLAN tags and restricts traffic to a single VLAN, preventing multi-VLAN trunking.

Enable 802.1Q trunking on the interface

Interface mode switches to trunking.

Running 'switchport mode trunk' forces the switchport into permanent trunking mode.

Modify the trunk allowed VLAN list

VLAN 30 is appended to the allowed VLANs list on the trunk link.

Using 'switchport trunk allowed vlan add 30' allows frames tagged with VLAN 30 to cross the trunk interface without removing existing allowed VLANs.

Anahtar Kavram

802.1Q Trunking Mode Configuration and Allowed VLAN List Management

Soru 1929Soru →

A network administrator is troubleshooting an existing Category 6 UTP cabling run between a floor switch and a wall outlet. Although a basic wiremapper confirms full pin-to-pin continuity and proper TIA/EIA 568B wire map alignment, connected devices experience frequent Frame Check Sequence (FCS) errors and link degradation during heavy traffic. Which of the following diagnostic tools should the administrator use to locate the exact position of the physical cable damage along the run?

Time-Domain Reflectometer (TDR)

Tone generator and inductive probe

Optical Power Meter (OPM)

Loopback plug

Cevabı ve açıklamayı göster

Cevap: Time-Domain Reflectometer (TDR)

Cevap

Time-Domain Reflectometer (TDR)

A Time-Domain Reflectometer (TDR) transmits electrical pulses along metallic copper conductors and measures signal reflections caused by impedance discontinuities. By measuring the round-trip time of the reflected wave, the TDR accurately calculates the distance to cable kinks, breaks, or severe NEXT/crosstalk points.

Adım Adım Çözüm

Analyze the symptoms and current test results.

Basic wiremapping confirms pin continuity, but physical layer frame corruption (FCS errors) indicates physical damage or impedance mismatches along the copper cable run.

Standard continuity testers only verify basic pin-to-pin connections and cannot detect signal degradation or locate internal conductor flaws.

Select the appropriate physical diagnostic tool for copper media.

A Time-Domain Reflectometer (TDR) is selected because it transmits electrical signals down copper conductors and calculates fault distance based on reflection timing.

TDR technology accurately measures distance to impedance changes, cable kinks, or partial breaks in copper twisted-pair cabling.

Anahtar Kavram

Selecting copper cabling diagnostic tools for distance-to-fault analysis

Tahmini Süre:1m 0s

Soru 1930Soru →

A network security analyst auditing firewall logs observes traffic originating from an internal host with IP address $10.50.84.142/21$ . To configure a targeted network access rule, the analyst must determine the exact boundaries of the local subnet. Which of the following identifies the correct network address and broadcast address for the subnet containing this host?

Network address

10.50.80.0

and broadcast address

10.50.87.255

Network address

10.50.84.0

and broadcast address

10.50.84.255

Network address

10.50.80.0

and broadcast address

10.50.88.255

Network address

10.50.80.1

and broadcast address

10.50.87.254

Cevabı ve açıklamayı göster

Cevap: Network address $10.50.80.0$ and broadcast address $10.50.87.255$

Cevap

Network address

10.50.80.0

and broadcast address

10.50.87.255

For the host IP address

10.50.84.142/21

, the

/21

mask corresponds to

255.255.248.0

. The third octet operates in block increments of

8

. The network boundary starts at

80

(

10 \times 8

), making the network address

10.50.80.0

. The subnet spans from

10.50.80.0

through

10.50.87.255

, establishing

10.50.87.255

as the broadcast address.

Adım Adım Çözüm

Determine the subnet mask from the CIDR prefix length

/21

/21

mask has

21

network bits:

255.255.248.0

Converting CIDR notation to dotted-decimal format identifies which octet contains the subnet boundary.

Calculate the block size (increment) in the third octet.

Block size =

256 - 248 = 8

Subnet boundaries in the third octet recur in multiples of

8

Identify the network address by finding the highest multiple of

8

less than or equal to the host's third octet (

84

Multiples of

8

0, 8, 16, \dots, 72, 80, 88

. Since

80 \leq 84 < 88

, the network third octet is

80

. Network address =

10.50.80.0

The network address uses all zeros in the host portion.

Calculate the broadcast address for this subnet.

The next subnet begins at

10.50.88.0

, so the broadcast address is

10.50.87.255

The broadcast address is one IP less than the next subnet's network address (all host bits set to 1).

Anahtar Kavram

IPv4 Subnet Boundaries and Broadcast Address Calculation

Tahmini Süre:1m 30s

Soru 1931Soru →

A network administrator is troubleshooting an issue where external mail gateways reject outbound emails sent from `example.com` due to failed Sender Policy Framework (SPF) validation checks. The administrator executes the following `dig` commands to inspect the DNS domain records:

text
$ dig MX example.com +short
10 mail01.example.com.

$ dig A mail01.example.com +short
192.0.2.25

Which of the following DNS resource records must be created in the `example.com` DNS zone to resolve the SPF validation failures?

A TXT record containing a policy string that explicitly designates authorized sending mail servers and IP addresses for the domain

A CNAME record aliasing `mail01.example.com` to `spf.example.com` to delegate authentication handling

An MX record with a lower preference value specifically designated for SPF verification traffic

A PTR record mapping TCP port 25 directly to `mail01.example.com` for reverse transport protocol authentication

Cevabı ve açıklamayı göster

Cevap: A TXT record containing a policy string that explicitly designates authorized sending mail servers and IP addresses for the domain

Cevap

The network administrator must create a TXT record that specifies the SPF policy string containing authorized IP addresses and mail servers for the domain.

The option specifying a TXT record containing a policy string is correct because SPF relies on machine-readable text records in DNS to list authorized sending hosts and IP addresses for a domain.

Adım Adım Çözüm

Identify the purpose of Sender Policy Framework (SPF).

SPF is an email authentication protocol designed to detect email spoofing by verifying sender IP addresses.

Receiving email systems validate incoming messages against sender rules published in the domain's public DNS.

Evaluate which DNS record type stores SPF policy statements.

SPF mechanisms and policies are defined using standard DNS TXT resource records.

TXT records store arbitrary human-readable and machine-readable text strings, including SPF, DKIM, and DMARC authentication records.

Anahtar Kavram

DNS Record Types and Mail Security (TXT for SPF/DKIM/DMARC)

Soru 1932Soru →

A network administrator deploys a new workstation on VLAN 35 ( $10.35.0.0/24$ ). Upon booting up, the workstation cannot access internal servers or the internet. Executing `ipconfig /all` on the workstation yields the following output:

IPv4 Address. . . . . . . . . . . : 169.254.14.88
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : Yes

The central DHCP server is located on VLAN 10 ( $10.10.0.0/24$ ) and actively provides IP address leases to clients on VLAN 10. Which of the following represents the most likely cause of this issue?

The Layer 3 interface serving VLAN 35 lacks an IP helper address pointing to the DHCP server.

The workstation has been manually assigned an invalid static default gateway address.

The central DHCP server's scope pool for VLAN 10 has exhausted all available host IP addresses.

The workstation's default gateway resides on a different IP subnet than the host.

Cevabı ve açıklamayı göster

Cevap: The Layer 3 interface serving VLAN 35 lacks an IP helper address pointing to the DHCP server.

Cevap

The Layer 3 interface serving VLAN 35 lacks an IP helper address pointing to the DHCP server.

The client address

169.254.14.88

indicates that the workstation failed to receive a response to its DHCP DISCOVER broadcast and fell back to Automatic Private IP Addressing (APIPA). Because the DHCP server is on a different subnet (VLAN 10), the router interface serving VLAN 35 must be configured with a DHCP Relay Agent (`ip helper-address`) to forward client broadcast requests to the unicast IP address of the DHCP server.

Adım Adım Çözüm

Analyze host network configuration output.

The workstation has an IPv4 address of

169.254.14.88

with a

/16

mask (

255.255.0.0

) and no default gateway.

Addresses in the range

169.254.0.1

through

169.254.255.254

represent Automatic Private IP Addressing (APIPA), indicating the client tried and failed to contact a DHCP server.

Evaluate network topology and DHCP traffic flow boundaries.

The host is on VLAN 35 (

10.35.0.0/24

), while the DHCP server resides on VLAN 10 (

10.10.0.0/24

DHCP discovery messages are sent as Layer 2 broadcast packets (

255.255.255.255

). Routers do not forward Layer 2 broadcasts across subnets by default.

Identify missing relay component.

A DHCP Relay Agent (such as `ip helper-address` on a router or Layer 3 switch interface) is required on VLAN 35 to forward broadcast requests as unicast packets to the DHCP server on VLAN 10.

Without an IP helper address configured on VLAN 35's default gateway interface, DHCP DISCOVER broadcasts are dropped by the router.

Anahtar Kavram

DHCP Relay Agent and APIPA Diagnosis

Tahmini Süre:1m 15s

Soru 1933Soru →

A field engineer is reviewing wireless site survey findings for a newly commissioned office space. The survey report reveals high frame corruption rates caused by adjacent channel interference in the $2.4\text{ GHz}$ spectrum. Upon inspecting the wireless LAN controller, the engineer notices that three neighboring access points are currently configured to operate on channels $1$ , $3$ , and $5$ with a $20\text{ MHz}$ channel width. Which channel reassignment scheme should the engineer implement to eliminate adjacent channel overlap?

Reassign the access points to channels

1

6

, and

11

Reassign the access points to channels

2

4

, and

6

Reassign the access points to channels

1

5

, and

9

Enable

40\text{ MHz}

channel bonding across channels

1

and

5

Cevabı ve açıklamayı göster

Cevap: Reassign the access points to channels $1$ , $6$ , and $11$ .

Cevap

Reassign the access points to channels

1

6

, and

11

In the

2.4\text{ GHz}

wireless spectrum, each channel operates with a

20\text{ MHz}

width (with a

22\text{ MHz}

signal mask) and center frequencies are spaced only

5\text{ MHz}

apart. Therefore, channels must be separated by at least 5 channel increments to avoid spectral overlap. Channels 1, 6, and 11 are the three standard non-overlapping

20\text{ MHz}

channels in North America.

Adım Adım Çözüm

Identify the operating frequency band and channel width.

The deployment uses the

2.4\text{ GHz}

band with

20\text{ MHz}

wide channels.

Understanding the band characteristics dictates how channels overlap.

Calculate required channel separation to prevent overlap.

Each

20\text{ MHz}

channel occupies

22\text{ MHz}

of spectral width (

11\text{ MHz}

above and below the center frequency), requiring at least

5

channel numbers of separation.

Channels closer than 5 channel numbers apart share overlapping frequency bounds.

Select the standard non-overlapping channels for the region.

Channels

1

6

, and

11

provide

25\text{ MHz}

spacing between center frequencies, fully isolating each cell.

Using channels 1, 6, and 11 avoids adjacent channel interference entirely.

Anahtar Kavram

2.4 GHz Non-Overlapping Channels

Tahmini Süre:1m 0s

Soru 1934Soru →

A network technician is investigating performance issues on several newly installed cabling runs connecting a distribution switch to server racks. The technician needs to identify appropriate diagnostic procedures and remedies for physical layer faults. Which of the following actions and tool selections correctly resolve these physical layer problems? (Select TWO.)

Geçerli olan tümünü seçin

Use an Optical Power Meter (OPM) to measure signal power loss across a fiber optic patch link suspect of excessive attenuation.

Reterminate an RJ-45 connector on a Category 6 UTP cable using consistent T568B pinouts on both ends to resolve a split pair condition.

Use a tone generator and inductive probe kit to pinpoint the exact distance to a severed conductor inside a copper conduit.

Use a basic continuity wiremapper to calculate Near-End Crosstalk (NEXT) and attenuation on high-speed copper cabling drops.

Cevabı ve açıklamayı göster

Cevap: Use an Optical Power Meter (OPM) to measure signal power loss across a fiber optic patch link suspect of excessive attenuation.; Reterminate an RJ-45 connector on a Category 6 UTP cable using consistent T568B pinouts on both ends to resolve a split pair condition.

Cevap

The correct responses are using an Optical Power Meter (OPM) to measure light attenuation across a fiber link, and reterminating Category 6 UTP cable connectors with consistent T568B pinouts to correct split pairs.

Measuring fiber power loss requires an Optical Power Meter (OPM) to test light intensity, while resolving split pairs on twisted-pair cables requires reterminating connectors consistently to a standard such as T568B so that signals travel along paired twists.

Adım Adım Çözüm

Evaluate fiber optic diagnostic requirement

Identify that light loss / attenuation along a fiber link is directly measured in dB or dBm using an Optical Power Meter combined with a light source.

OPM is the standard instrument for validating fiber optic power levels and decibel loss.

Identify corrective action for split pairs on copper twisted-pair cabling

Recognize that split pairs result from incorrect pin assignment configurations across twisted pairs and require proper retermination according to TIA/EIA-568 standards.

Reterminating both ends to standard T568B ensures corresponding signals travel along correctly twisted pairs, minimizing NEXT.

Analyze incorrect tool selection choices

Distinguish between wire tracing tools (tone probe), basic continuity testers (wiremapper), and distance/performance diagnostics (TDR / Cable Certifier).

Tone probes trace cables and wiremappers check simple continuity, but neither locate fault distances or measure high-frequency noise.

Anahtar Kavram

Selecting accurate testing equipment (OPM vs TDR vs tone probe) and applying standard cable termination (T568A/B) to resolve copper and fiber physical layer faults.

Tahmini Süre:1m 30s

Soru 1935Soru →

An enterprise network administrator configures a backup schedule where a full backup is executed every Sunday at 01:00 AM, and differential backups are executed daily at 11:00 PM from Monday through Saturday. On Thursday at 03:00 PM, a primary storage array suffers an unrecoverable disk crash. Which of the following represents the minimum sequence of restoration jobs required to recover the system to its latest available backup state?

Restore the Sunday full backup, followed by the Wednesday differential backup.

Restore the Sunday full backup, followed sequentially by the Monday, Tuesday, and Wednesday differential backups.

Restore the Sunday full backup, followed by the Thursday differential backup.

Restore only the Wednesday differential backup directly to the storage volume.

Cevabı ve açıklamayı göster

Cevap: Restore the Sunday full backup, followed by the Wednesday differential backup.

Cevap

Restore the Sunday full backup, followed by the Wednesday differential backup.

Differential backups accumulate all changes made since the last full baseline backup. Consequently, recovering a system configured with a full baseline and differential backups requires restoring the full backup first, followed strictly by the single most recent differential backup set (Wednesday at 11:00 PM).

Adım Adım Çözüm

Analyze the backup type and execution schedule relative to the failure time.

The system utilizes a Sunday full backup baseline and daily 11:00 PM differential backups. The failure occurred Thursday at 03:00 PM.

The Thursday differential backup job has not executed yet, making Wednesday's 11:00 PM backup the latest completed differential set.

Identify the mandatory baseline restoration file.

The Sunday full backup must be restored first.

Differential backup sets do not contain the baseline file system structure or unmodified data and depend entirely on the preceding full backup.

Determine the minimal differential backup restoration steps required.

Apply only the Wednesday differential backup.

Each differential backup cumulatively includes all changes since the last full backup, so intermediate differential backups (Monday and Tuesday) are superseded by the Wednesday backup.

Anahtar Kavram

Differential Backup Restoration Mechanics

Tahmini Süre:1m 30s

Soru 1936Soru →

Match each DNS resource record type on the left with its corresponding technical function or usage scenario on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

SRV record matches service location parameters (hostname, port, priority, weight); PTR record matches reverse IP-to-hostname mapping; SOA record matches zone administration metadata and timers; CNAME record matches domain alias-to-canonical name mapping.

Each DNS record type has a dedicated function within network infrastructure: SRV specifies service locators and ports; PTR provides reverse name lookup; SOA provides zone administrative metadata and serial numbers; CNAME aliases hostnames to target canonical domain names.

Adım Adım Çözüm

Identify the record type designed to locate specific network services and ports.

Match the SRV record to the description detailing hostname, port, priority, and weight parameters.

SRV records are unique in providing both service port and target hostname along with load-balancing parameters.

Identify the record type used for reverse name resolution.

Match the PTR record to the description mapping IP addresses back to canonical hostnames.

PTR records reside in reverse lookup zones (in-addr.arpa or ip6.arpa) to fulfill reverse queries.

Identify the record that establishes authority and zone transfer properties for a DNS zone.

Match the SOA record to the description containing primary master server metadata, contact email, and zone timers.

The SOA record mandatory header marks the beginning of authority for every DNS zone file.

Identify the record type that creates an alias to an existing domain name.

Match the CNAME record to the description aliasing one domain name to a canonical domain name.

CNAME records redirect DNS queries for an alias directly to another hostname.

Anahtar Kavram

DNS Resource Record Types and Technical Functions

Soru 1937Soru →

A network administrator is troubleshooting an issue where a newly connected Linux host receives an IP address via DHCP but cannot communicate with hosts on external subnets. Arrange the following diagnostic and troubleshooting steps into the correct chronological order according to standard Network+ troubleshooting methodology.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct troubleshooting sequence begins with verifying physical link status, inspecting the local IP address and routing table for the default gateway, pinging the local default gateway, pinging a remote public IP address, and finally testing DNS domain name resolution.

Following standard CompTIA troubleshooting methodology, network diagnostics proceed logically from Layer 1 to higher layers: verify physical link integrity, inspect local IP and routing parameters (default gateway), test local subnet gateway reachability via ICMP, test external path routing via IP ping, and finally test higher-layer application services like DNS name resolution.

Adım Adım Çözüm

Check physical layer connectivity

Confirmed physical link integrity

Lower-layer physical connectivity issues must be ruled out before inspecting protocol-layer configuration.

Inspect IP configuration and default gateway entry

Identified configured IP address, subnet mask, and default gateway router address

Determines if the DHCP server supplied valid addressing details including the default gateway route.

Ping the local default gateway

Verified local subnet Layer 3 communication

Tests basic local packet forwarding and ARP resolution to the local router interface.

Ping a remote external IP address

Verified remote IP routing past the local gateway

Isolates network layer routing path issues from higher-level application/DNS issues.

Test DNS resolution with dig or nslookup

Verified full end-to-end service availability

Ensures domain names resolve to IP addresses after underlying IP reachability is established.

Anahtar Kavram

Standardized bottom-up IP addressing and DHCP service troubleshooting sequence

Soru 1938Soru →

A network administrator is conducting a comprehensive network analysis on a workstation experiencing connectivity and resolution issues. Match each command-line utility command on the left with its primary diagnostic function on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

pathping 192.168.10.1 matches with measuring packet loss and latency per hop; arp -a matches with displaying local MAC address mappings; netstat -ano matches with listing active connections, listening ports, and Process IDs; dig -x 10.0.0.50 matches with performing reverse DNS lookups.

Each command-line tool maps directly to its intended OSI layer and operational troubleshooting purpose: pathping measures per-hop packet loss over time, arp -a displays Layer 2 MAC cache tables, netstat -ano correlates listening sockets to Process IDs, and dig -x performs reverse DNS resolution.

Adım Adım Çözüm

Identify pathping functionality

pathping combines ICMP echo requests with route tracking over several minutes to report specific hop-by-hop packet loss stats.

This pinpoints intermittent link degradation across intermediate routers.

Identify arp -a functionality

arp -a queries the ARP cache on local interfaces.

ARP operates between Layer 2 and Layer 3 to resolve IP addresses to hardware MAC addresses.

Identify netstat -ano functionality

netstat with flags -a (all sockets), -n (numerical format), and -o (owning Process ID) outputs active network transport sockets.

This allows administrators to identify which local running processes are holding open listening ports or connections.

Identify dig -x functionality

dig -x executes a PTR record query against the configured DNS resolver.

The -x flag specifies a reverse lookup parameter to translate an IP address into a domain hostname.

Anahtar Kavram

Command-Line Network Diagnostic Utilities

Soru 1939Soru →

A network administrator is troubleshooting connectivity for a workstation on a newly configured VLAN 25 ( $172.16.25.0/24$ ). The central DHCP server is located on VLAN 10 ( $172.16.10.100$ ). Running `ipconfig /all` on the workstation yields the following output snippet:

IPv4 Address. . . . . . . . . . . : 169.254.88.12
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . :

Which of the following is the most likely cause of this issue?

The router interface serving VLAN 25 lacks a configured IP helper address pointing to the central DHCP server.

The client workstation was configured with an incorrect default gateway subnet mask, causing DHCP request drops.

The network interface assigned an APIPA address because the client's static IP configuration conflicts with the default gateway.

The DHCP scope for VLAN 25 exhausted its address space because unusable network and broadcast addresses were included as valid host allocations.

Cevabı ve açıklamayı göster

Cevap: The router interface serving VLAN 25 lacks a configured IP helper address pointing to the central DHCP server.

Cevap

The router interface serving VLAN 25 lacks a configured IP helper address pointing to the central DHCP server.

DHCP clients broadcast DHCPDISCOVER messages on their local subnet. Because routers do not forward Layer 3 broadcast traffic by default, clients on subnets separate from the central DHCP server cannot obtain an IP address unless an IP helper address (DHCP relay) is configured on the router gateway interface. Without a relay, the client times out and assigns itself an APIPA address (

169.254.x.x

Adım Adım Çözüm

Analyze the `ipconfig /all` output snippet provided for the workstation.

The workstation has self-assigned an APIPA address (

169.254.88.12

) with no Default Gateway or DHCP Server listed.

When a client configured for dynamic IP addressing fails to receive a response to its DHCPDISCOVER broadcast, operating systems default to Automatic Private IP Addressing (APIPA).

Evaluate the network topology details.

The client resides on VLAN 25 (

172.16.25.0/24

), whereas the DHCP server resides on a different subnet, VLAN 10 (

172.16.10.100

Layer 3 routers block broadcast traffic by default, preventing DHCPDISCOVER broadcasts on VLAN 25 from reaching VLAN 10.

Identify the required network configuration for cross-subnet DHCP.

An IP helper address (DHCP relay agent) must be configured on the router's VLAN 25 interface.

The DHCP relay agent intercepts local DHCP broadcasts and forwards them as unicast packets across the router to the central DHCP server address.

Anahtar Kavram

DHCP Relay (IP Helper) Configuration across VLAN boundaries

Tahmini Süre:1m 15s

Soru 1940Soru →

Match each switch log message or port status indicator on the left with its corresponding root cause on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

The CDP native VLAN mismatch log corresponds to mismatched untagged VLAN IDs across a trunk link. Increasing late collisions and FCS errors correspond to a duplex mismatch between connected interfaces. The STP superior BPDU blocked port log corresponds to an unexpected switch advertising a lower STP priority. The inactive access port condition corresponds to a missing VLAN definition in the local switch VLAN database.

Each switch log or status symptom maps directly to a distinct Layer 2 misconfiguration: CDP warning logs pinpoint native VLAN mismatches, late collisions indicate duplex mismatches, superior BPDU logs indicate STP priority conflicts, and inactive port assignments indicate uncreated local VLANs.

Adım Adım Çözüm

Analyze the CDP native VLAN mismatch syslog notification

Identified explicit native VLAN mismatch (VLAN 10 vs VLAN 20) on trunk interface GigabitEthernet0/1.

802.1Q trunks must agree on the native VLAN ID to prevent cross-VLAN traffic leaks and CDP error logging.

Analyze the interface error counters showing late collisions and FCS errors

Identified classic duplex mismatch diagnostic indicators.

Half-duplex interfaces listen before transmitting, but when connected to a full-duplex port, collisions occur late in frame transmission.

Analyze the Spanning Tree Protocol port blocking message

Associated superior BPDU receipt with STP root bridge election dynamics.

A superior BPDU contains a lower Bridge ID (Priority + MAC), causing STP to block or re-evaluate path priorities to prevent loops.

Analyze the inactive access port state for assigned VLAN 40

Correlated the inactive port symptom with missing database configuration.

Access ports assigned to a non-existent VLAN cannot forward traffic until the VLAN is defined in the VLAN database.

Anahtar Kavram

Troubleshooting Layer 2 switching issues including native VLAN mismatches, duplex misconfigurations, STP topology dynamics, and missing VLAN database entries.

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