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Zorluk: OrtaTroubleshooting IP Addressing and DHCP Services

A network technician is troubleshooting connectivity issues for several newly provisioned workstations on the finance VLAN (10.15.30.0/24). While the workstations can communicate with each other on the local switch, none of them can access corporate servers on external subnets or reach the internet. An inspection of `ipconfig /all` on one of the affected clients yields the following output:

IPv4 Address. . . . . . . . . . . : 10.15.30.45
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.15.40.1
DHCP Server . . . . . . . . . . . : 10.15.10.10

Which of the following is the most likely cause of the routing failure?

  1. The DHCP scope option for the default gateway specifies an IP address located outside the local subnet.Cevap
  2. B
    The client host failed to acquire an IP lease from the DHCP server and generated an APIPA address.
  3. C
    The local switch interface is missing an IP helper address required to forward DHCP request broadcasts.
  4. D
    The DHCP address pool for the 10.15.30.0/24 subnet has exhausted all available usable host addresses.

Cevap

The DHCP scope option for the default gateway specifies an IP address located outside the local subnet.
For a workstation to communicate with remote networks, its configured default gateway must share the same network identifier as defined by the host IP address and subnet mask. In this scenario, the host IP (10.15.30.45/24) belongs to the 10.15.30.0/24 subnet, but the gateway (10.15.40.1) resides on 10.15.40.0/24. This subnet mismatch prevents ARP resolution for the default gateway, resulting in failed off-subnet routing while allowing local switch traffic.

Adım Adım Çözüm

1
Analyze the IP address and subnet mask from the command output.
The host IP is 10.15.30.45 with subnet mask 255.255.255.0 (/24). The local network boundary is 10.15.30.0 to 10.15.30.255.
Determines which IP addresses reside on the local broadcast domain.
2
Compare the configured default gateway address against the local subnet range.
The default gateway is configured as 10.15.40.1, which falls into the 10.15.40.0/24 subnet rather than 10.15.30.0/24.
A default gateway must reside on the same IP subnet as the client host to receive local Layer 2 frames.
3
Determine the root cause of off-subnet unreachability.
Because the gateway IP is non-local, client traffic destined for external networks cannot be delivered to the gateway router.
Confirms why local switch traffic functions properly while external/internet routing fails.

Anahtar Kavram

Default Gateway Subnet Alignment in DHCP Scope Configurations
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Konular

Troubleshooting IP Addressing and DHCP Services

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