NCoE Selection Test case studies
NCoE Selection Test · Put your knowledge to work in context.
The NCoE Selection Test is a skills-based screening exam used to identify engineers ready to work in a Network Center of Excellence environment. It is aimed at network professionals who already hold foundational certification-level knowledge and now need to demonstrate operational judgement: reading a topology, choosing a path, hardening access, and diagnosing faults under time pressure. The NCoE Selection Test case studies are 5 cases and about 4,745 words.
1OSPF Stuck in EXSTART After a 10G Core Cutover, Then a Summary Black Hole
Northgate Data Center replaced the 1 Gbps core link between CORE-A (IOS-XE) and CORE-B (EOS) with 10 Gbps optics during a Saturday window. OSPFv2 area 0 is the IGP; both routers also carry floating static routes that are currently forwarding production traffic, so users see no outage but redundancy is gone.
973 words, about 5 min2400 Wired Endpoints Fall to the Guest VLAN After a PKI and RADIUS Certificate Change
Halden Manufacturing runs 802.1X on 42 access switches for about 1,200 endpoints. Wired endpoints use EAP-TLS with machine certificates from a 3-year internal PKI; printers and building-management controllers use MAB; successful authentication assigns a dynamic VLAN.
952 words, about 5 min3Scope Exhaustion at 89% With Only 780 Active Devices, Plus DNS SERVFAIL on a Partner Zone
Ridgeway Health's campus serves 1,400 staff devices from a single DHCP scope, 10.30.4.0/22 (1,022 usable addresses), with 8-day leases. Two Windows Server 2022 DHCP servers share the scope 80/20 with no failover relationship; relays sit on the distribution switches, and Option 82 is enabled with snooping on access ports and uplinks trusted.
928 words, about 5 min4Daily 10:00 POS Timeouts Behind a 45% Utilization Reading
Tarnfield Retail runs a 200 Mbps MPLS hub-and-spoke from a data center CE to 60 stores, with an IPsec internet backup that is not used for production traffic. Store POS transactions hit a SQL application in the DC and have timed out daily between 10:00 and 11:00 for three weeks.
929 words, about 5 min5A Nightly Ansible Run Leaves 60 of 180 Switches Half-Configured
Kestrel Logistics manages 180 Cisco access switches across 12 sites with Ansible 2.16 over network cli . A nightly playbook adds VLANs and applies a standard edge ACL; inventory comes from NetBox through a dynamic plugin.
963 words, about 5 min