All hosts in a network have already received IP configuration from a DHCP server. Several hours later the DHCP server fails. What happens to these hosts?

Introduction / Context:
Dynamic Host Configuration Protocol servers assign IP addresses and related configuration to client devices on a network. Understanding what happens if the DHCP server becomes unavailable is important for diagnosing connectivity issues and planning network redundancy. Many administrators worry that a DHCP outage will instantly disconnect users, but the behavior is controlled by the lease mechanism.

Given Data / Assumptions:

• All hosts obtained their IP settings earlier from a functioning DHCP server.
• After several hours, the DHCP server goes down and cannot respond to requests.
• No configuration changes are made on the clients when the server fails.
• DHCP clients are using standard lease renewal behavior defined by the protocol.

Concept / Approach:
When a DHCP client obtains an IP address, it also receives a lease time indicating how long it may use that address. Until the lease expires, the client treats the configuration as valid and continues normal operation. The client begins to renew the lease before expiration, usually at half the lease duration. If the server is unreachable, renewal attempts fail, but the client still retains the address until the lease finally expires. Therefore, the client does not lose connectivity immediately when the server goes down.

Step-by-Step Solution:
1. A DHCP client obtains an IP address, subnet mask, gateway, and DNS information, along with a lease time.2. The client uses this configuration for normal communication on the network.3. When the DHCP server fails, the client is not automatically notified.4. The client keeps using the leased address; only when the renewal time is reached does it attempt to contact the server.5. If the server remains down until the lease expires, the client may then lose its address; until then, communication continues as usual.

Verification / Alternative check:
You can verify this behavior by inspecting a client's IP configuration and lease times. On many operating systems, commands such as ipconfig or similar tools show the lease obtained and expiry time. Observing a running network during a planned DHCP outage confirms that existing clients continue to work until their leases age out.

Why Other Options Are Wrong:
Option A is incorrect because clients do not lose connectivity immediately when the server fails. Option C is incorrect because the ability to communicate inside or outside the network is unrelated to the server's current status; it depends on the IP configuration already in place. Option D is incorrect because name resolution continues to work as long as DNS settings are valid and DNS servers remain reachable, independent of the DHCP server itself.

Common Pitfalls:
Many learners assume that DHCP acts like a continuous control plane, where server failure instantly breaks client connectivity. In reality, DHCP is mostly used during initial configuration and renewal. Another pitfall is forgetting about the lease time, leading to confusion when some devices lose connectivity later while others continue to function, depending on when each lease expires.

Final Answer:
They continue to communicate normally until their DHCP leases expire.