Refer To The Exhibit. A Network Administrator Is Configuring

When a network administrator refers to the exhibit while configuring a new VLAN‑based routing solution, the diagram serves as both a visual checklist and a troubleshooting guide that ensures every interface, IP address, and routing protocol aligns with the documented design. This article walks through the typical workflow, explains the underlying concepts, and highlights best practices so that anyone studying for a certification—or managing a production network—can replicate the configuration with confidence.

Introduction

Network diagrams, often labeled as “exhibits” in lab manuals or vendor documentation, provide a snapshot of the intended topology. When the instruction says “refer to the exhibit. a network administrator is configuring”, it signals that the administrator must cross‑check each step against the pictured devices, ports, and IP schemes before issuing any commands. Ignoring the exhibit can lead to mismatched subnets, duplicate addresses, or routing loops that are difficult to trace later. By treating the exhibit as the authoritative source, the administrator builds a configuration that is both accurate and auditable.

Understanding the Exhibit Before touching the CLI, the administrator should spend a few minutes interpreting the exhibit:

1. Device roles – Identify which boxes are routers, switches, firewalls, or end hosts.
2. Interface labeling – Note the exact port numbers (e.g., GigabitEthernet0/1) and whether they are access, trunk, or routed ports.
3. Addressing scheme – Verify the IPv4/IPv6 subnets assigned to each VLAN or point‑to‑point link.
4. Protocol hints – Look for annotations such as “OSPF area 0” or “EIGRP AS 100” that indicate which routing protocol should be active.
5. Special features – Some exhibits mark QoS policies, NAT translations, or VPN tunnels that must be configured separately.

By extracting this information into a quick reference table, the administrator reduces the chance of copying errors when moving from the diagram to the command line.

Step‑by‑Step Configuration Process Below is a typical sequence that a network administrator follows when the exhibit depicts a three‑router OSPF network with two VLANs on a distribution switch. Adjust the steps to match your specific exhibit, but keep the logical order: plan → verify → implement → validate.

1. Prepare the Workspace

• Console into each device using the exhibit’s console port labels.
• Save the current running configuration (copy running-config startup-config) as a rollback point.
• Enable logging (logging buffered 10000) to capture any errors during the process.

2. Configure Basic Device Settings

3. Assign IP Addresses to Interfaces

Using the exhibit’s IP plan, apply addresses to each interface. For point‑to‑point links, use /30 subnets; for VLANs, use the designated /24.

! On R1 – interface facing SW1
interface GigabitEthernet0/0 ip address 10.0.10.1 255.255.255.0
 no shutdown

Repeat for every link, double‑checking that the subnet mask matches the exhibit.

4. Create and Map VLANs (Switch)

If the exhibit shows VLAN 10 (Sales) and VLAN 20 (Engineering) on SW1:

 name Sales
vlan 20
 name Engineering
!
interface range GigabitEthernet0/1 - 0/2
 switchport mode access
 switchport access vlan 10!
interface range GigabitEthernet0/3 - 0/4
 switchport mode access
 switchport access vlan 20
!
interface GigabitEthernet0/5
 switchport mode trunk
 switchport trunk allowed vlan 10,20

5. Enable Routing Protocol (OSPF Example)

The exhibit may indicate OSPF area 0 for all routers. Configure OSPF with the network statements that match the exhibited subnets.

router ospf 1
 network 10.0.10.0 0.0.0.255 area 0
 network 10.0.20.0 0.0.0.255 area 0
 network 10.0.30.0 0.0.0.255 area 0
!

6. Verify Connectivity - Ping each neighbor’s IP address from every router.

• Use show ip ospf neighbor to confirm adjacency states are FULL.
• On the switch, run show vlan brief and show interfaces trunk to ensure VLANs are correctly mapped.

7. Save and Document

• Save the configuration on each device (write memory or copy running-config startup-config).
• Update the network diagram with any changes made (e.g., added loopback interfaces for router IDs).

Following this methodical approach ensures that the configuration mirrors the exhibit exactly, minimizing the risk of misconfiguration.

Key Technologies and Protocols Involved

Understanding why each step is necessary helps the administrator troubleshoot when something does not match the exhibit.

IP Addressing and Subnetting

The exhibit’s IP plan is rooted in hierarchical addressing. Proper sub

The exhibit’s IP plan is rooted in hierarchical addressing. Proper subnetting ensures that each network segment receives just enough address space while leaving room for growth. When designing the subnets, start with the largest required block (often a /24 for a VLAN) and then carve out smaller /30 or /31 subnets for point‑to‑point links. This approach conserves address space, simplifies route summarization, and reduces the size of the routing tables on each device. Remember to verify that the subnet masks you apply on interfaces exactly match the masks listed in the exhibit; a single‑bit mismatch will cause OSPF to reject the network statement and break adjacency.

VLAN Trunking and Spanning‑Tree Protocol

On the switch side, VLANs create logical broadcast domains that must be carried across trunk links to other switches or routers. The switchport mode trunk command, together with switchport trunk allowed vlan, restricts the trunk to only the VLANs defined in the exhibit, preventing unnecessary broadcast traffic and enhancing security. After configuring the trunks, enable Rapid PVST+ (or MSTP if the design calls for multiple spanning‑tree instances) to guarantee a loop‑free topology. Use show spanning-tree summary to confirm that the root bridge is placed as intended and that all ports are either forwarding or blocking according to the exhibit’s STP plan.

OSPF Specifics

When OSPF is the chosen IGP, pay attention to the following details that often trip up administrators:

1. Router ID – If not manually set with router-id <IP>, OSPF will select the highest loopback address or the highest active IP. Align the router ID with the exhibit’s documentation to avoid confusion during troubleshooting.
2. Passive Interfaces – Interfaces that connect to end‑user devices should be marked passive (passive-interface default then no passive-interface <interface> for links that need adjacency). This prevents unnecessary OSPF hello traffic on stub networks while still advertising those networks.
3. Area Design – The exhibit may call for a single area (area 0) or a multi‑area hierarchy. If multiple areas are used, ensure that ABRs are correctly configured with the appropriate area <range> statements for route summarization, which reduces LSDB size and improves convergence.
4. Authentication – If the exhibit specifies OSPF authentication (plain‑text or MD5), apply it under the OSPF process or per‑interface with ip ospf authentication-key or ip ospf message-digest-key. Mismatched authentication will cause neighbors to stay in the INIT state.

Verification Checklist

After completing the configuration, run through this concise verification list:

• IP Addressing – show ip interface brief confirms every interface has the correct address and subnet mask.
• VLANs – show vlan brief lists the expected VLANs and their names; show interfaces trunk verifies the allowed VLAN list matches the exhibit.
• SPT – show spanning-tree shows the designated root and port states; ensure no ports are stuck in blocking unless the exhibit explicitly calls for it.
• OSPF – show ip ospf neighbor displays FULL state for all expected adjacencies; show ip ospf interface confirms hello/dead intervals, area, and authentication settings.
• Connectivity – Extended ping and traceroute from each router to every other router’s loopback (if configured) and to representative hosts in each VLAN validate end‑to‑end reachability.

Documentation and Change Control

Finally, capture the exact configuration files (show run) and store them in a version‑controlled repository. Update the network diagram with any newly added loopbacks, VLANs, or OSPF areas, and annotate the diagram with the corresponding IP addresses and subnet masks. A clear, up‑to‑date record not only satisfies audit requirements but also accelerates future troubleshooting or expansion efforts.

By following the detailed steps above—starting with meticulous IP addressing and subnetting, progressing through VLAN and trunk configuration, fine‑tuning OSPF parameters, verifying spanning‑tree operation, and concluding with rigorous validation and documentation—you ensure that the live network mirrors the exhibit precisely. This methodical approach minimizes configuration drift, reduces the likelihood of human error, and provides a solid foundation for reliable, scalable network operations.