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Difficulty: MediumIP Addressing and Network Configuration

A network technician is troubleshooting several network connectivity issues reported across different workstations. Match each observed host diagnostic symptom to its underlying network configuration cause.

  • A workstation receives IP address 169.254.88.100 and can only communicate with other hosts on the immediate physical segment.DHCP server unreachability causing Automatic Private IP Addressing (APIPA) fallback.
  • A workstation configured with IP 192.168.10.45 can successfully ping 192.168.10.1, but pinging 8.8.8.8 returns 'Destination host unreachable'.Missing or improperly configured default gateway address.
  • A workstation configured with IP 10.0.4.12 can successfully ping 8.8.8.8, but navigating to web pages using domain names fails.Incorrect or unassigned Domain Name System (DNS) server configuration.
  • A workstation assigned 192.168.1.25 cannot reach host 192.168.1.200 on the same physical switch because its subnet mask is set to 255.255.255.240 instead of 255.255.255.0.Subnet mask mismatch placing target hosts into different logical subnets.

Answer

Matching pairs: (1) 169.254.88.100 APIPA address maps to DHCP server unreachability; (2) Ping to local gateway succeeds but remote IP fails maps to missing or invalid default gateway; (3) Remote IP ping succeeds but domain lookup fails maps to incorrect DNS server configuration; (4) 192.168.1.25 unable to reach 192.168.1.200 under 255.255.255.240 mask maps to subnet mask mismatch.
Each observed symptom maps directly to a specific IP layer parameter misconfiguration: 169.254.x.x indicates APIPA due to DHCP failure; successful local pings with failed remote pings point to missing default gateway settings; working IP pings with broken hostname resolution point to DNS failure; and inter-host isolation on the same physical segment with a /28 mask indicates a subnet mask boundary error.

Step-by-Step Solution

1
Analyze symptom 1 (169.254.88.100 IP address).
Recognize the 169.254.0.0/16 address space as APIPA assigned when DHCP server requests fail.
APIPA allows local link communication only when dynamic lease acquisition fails.
2
Analyze symptom 2 (Local ping succeeds, remote IP ping fails).
Determine that local Layer 2/3 traffic functions, but traffic destinated outside the subnet lacks a valid routing path.
The default gateway is required to forward traffic outside the local IP network.
3
Analyze symptom 3 (IP ping succeeds, domain name resolution fails).
Confirm IP routing works properly, meaning network layer connectivity is sound while name-to-IP translation fails.
DNS resolution converts domain names into numerical IP addresses.
4
Analyze symptom 4 (Host unable to contact IP on same switch due to 255.255.255.240 mask).
Calculate that a 255.255.255.240 mask restricts valid hosts to a smaller range (0-15, 16-31, etc.), placing .200 on another subnet.
An improperly tight subnet mask prevents direct local delivery by attempting to send local traffic to a gateway.

Key Concept

Identifying IP configuration parameters (APIPA, Gateway, DNS, Subnet Mask) through diagnostic symptoms and network behaviors.
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Topics

IP Addressing and Network Configuration

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