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Zorluk: OrtaIP Addressing and Network Configuration

A technician is troubleshooting network connectivity on a desktop computer connected to an enterprise local area network. The host can successfully ping other computers on the local subnet (10.20.4.0/2410.20.4.0/24), but users cannot access resources on remote subnets or reach internet services. Pinging an external address such as 8.8.8.88.8.8.8 results in a "Destination host unreachable" error message.

Executing `ipconfig /all` on the workstation displays the following network configuration parameters:

ParameterConfigured Value
IPv4 Address10.20.4.7810.20.4.78
Subnet Mask255.255.255.0255.255.255.0
Default Gateway10.20.5.110.20.5.1
DNS Server10.20.4.210.20.4.2

Which of the following configuration errors is the primary cause of the external connectivity issue?

  1. The default gateway IP address resides on a different IP subnet than the workstation.Cevap
  2. B
    The workstation failed to acquire a DHCP lease and automatically assigned itself an APIPA address.
  3. C
    The DNS server address is acting as a DHCP server and refusing to resolve default gateway hostnames.
  4. D
    The local unmanaged Layer 2 switch is improperly configured to route packets between subnets.

Cevap

The default gateway IP address resides on a different IP subnet than the workstation.
With a subnet mask of 255.255.255.0255.255.255.0, all devices on the local subnet must have IP addresses starting with 10.20.410.20.4. The gateway address 10.20.5.110.20.5.1 is on a different subnet (10.20.5.0/2410.20.5.0/24), making it unreachable directly by the workstation. Without a valid local default gateway, traffic targeting outside IP addresses (such as 8.8.8.88.8.8.8) cannot be routed off the local network.

Adım Adım Çözüm

1
Analyze host IPv4 network address and subnet bounds
IP 10.20.4.7810.20.4.78 with mask 255.255.255.0255.255.255.0 (/24/24) means local network valid host range is 10.20.4.110.20.4.1 through 10.20.4.25410.20.4.254.
Subnet mask 255.255.255.0255.255.255.0 restricts local communication to IP addresses matching the first three octets (10.20.4.x10.20.4.x).
2
Compare Default Gateway address to local network bounds
The configured default gateway is 10.20.5.110.20.5.1, which belongs to the 10.20.5.0/2410.20.5.0/24 network subnet.
For a client to forward packets outside its local network, its default gateway must be a reachable router interface located on the exact same local IP subnet.
3
Determine root cause of failure
Local traffic succeeds, but remote traffic fails because the gateway is unreachable due to a subnet mismatch.
Re-assigning the default gateway to an address in the 10.20.4.0/2410.20.4.0/24 range (e.g., 10.20.4.110.20.4.1) will restore external connectivity.

Anahtar Kavram

IP Subnetting and Default Gateway Assignment
Tahmini Süre:1m 15s
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