A system administrator is troubleshooting outbound connectivity on a Linux server. The ser… — CompTIA Network+

A system administrator is troubleshooting outbound connectivity on a Linux server. The server shows the following IPv4 network configuration:

- IP Address: $172.16.50.22$
- Subnet Mask: $255.255.255.0$ (/ $24$ )
- Default Gateway: $172.16.51.1$

The server can successfully communicate with local hosts on the $172.16.50.0/24$ network but cannot reach any external subnets or the internet. Which of the following best explains why the server cannot reach remote networks?

The default gateway is configured on a different IP subnet than the server's IP address.Answer
B
The default gateway IP address is invalid because addresses ending in .1 are reserved for network identifiers.
C
The server requires an active VLAN trunking protocol on its NIC to send packets past its local broadcast domain.
D
The default gateway is rejecting outbound packets due to a transport layer protocol port mismatch.

Answer

The server cannot communicate outside its local network because the default gateway (

172.16.51.1

) is on a different subnet than the server (

172.16.50.22/24

For a host to communicate with remote networks, its default gateway must reside within the exact same IP subnet as the host's network interface. Given an IP address of

172.16.50.22

and a subnet mask of

255.255.255.0

24

), the valid local host addresses span from

172.16.50.1

through

172.16.50.254

. The configured default gateway address of

172.16.51.1

is on a completely separate subnet (

172.16.51.0/24

). As a result, the server cannot send ARP requests to discover the router's MAC address, preventing all traffic destined for external networks.

Step-by-Step Solution

Determine the usable host IP address range for the server's configured network interface.

With IP

172.16.50.22

and Subnet Mask

255.255.255.0

24

), the subnet network address is

172.16.50.0

and usable host IP addresses range from

172.16.50.1

172.16.50.254

A default gateway must reside on the same logical Layer 3 IP subnet as the host interface so the host can resolve the gateway's MAC address via ARP.

Compare the configured default gateway address with the local subnet range.

The configured default gateway (

172.16.51.1

) belongs to the

172.16.51.0/24

subnet, which is outside the local

172.16.50.0/24

range.

Because the gateway is on a foreign subnet, the server cannot ARP for the gateway directly on its local broadcast domain.

Identify the corrective action required to restore remote connectivity.

Update the server's default gateway setting to a valid router IP address on the

172.16.50.0/24

subnet (such as

172.16.50.1

Ensuring IP and gateway subnet alignment permits proper ARP resolution and packet forwarding to remote networks.

Key Concept

Default Gateway Subnet Alignment

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic