CDCP Network Infrastructure and Connectivity 1 — Questions and Answers
Question 1: Which network topology is most commonly used within a data center to provide redundancy and high availability?
- Bus topology
- Ring topology
- Fat-tree (spine-leaf) topology (Correct answer)
- Star topology with single switch
Correct answer: Fat-tree (spine-leaf) topology
The fat-tree (spine-leaf) topology is preferred in data centers because it provides multiple equal-cost paths, eliminating single points of failure and enabling non-blocking bandwidth.
Question 2: What is the primary purpose of a Top-of-Rack (ToR) switch in a data center?
- To connect the data center to the internet
- To aggregate traffic from servers within a single rack before uplink to core switches (Correct answer)
- To provide out-of-band management for all network devices
- To perform deep packet inspection for security
Correct answer: To aggregate traffic from servers within a single rack before uplink to core switches
A ToR switch aggregates server connections within a rack and provides uplinks to distribution or spine-layer switches, reducing cable runs across the data floor.
Question 3: In data center networking, what does 'oversubscription ratio' refer to?
- The ratio of physical ports to virtual ports
- The ratio of total downstream bandwidth to available upstream bandwidth (Correct answer)
- The number of VLANs configured on a switch
- The ratio of active to passive network devices
Correct answer: The ratio of total downstream bandwidth to available upstream bandwidth
Oversubscription ratio describes how much downstream port bandwidth is shared across limited upstream bandwidth, e.g., a 4:1 ratio means four times more downstream capacity than upstream.
Question 4: Which protocol is used to prevent Layer 2 switching loops in a data center network?
- OSPF
- BGP
- Spanning Tree Protocol (STP) (Correct answer)
- MPLS
Correct answer: Spanning Tree Protocol (STP)
Spanning Tree Protocol (STP) and its variants (RSTP, MSTP) block redundant paths to prevent Layer 2 loops while maintaining failover capability.
Question 5: What is the recommended minimum fiber type for supporting 40GbE and 100GbE connections in modern data centers?
- OM1 multimode fiber
- OM2 multimode fiber
- OM3 or OM4 multimode fiber (Correct answer)
- Single-mode fiber only
Correct answer: OM3 or OM4 multimode fiber
OM3 and OM4 multimode fibers support 40GbE and 100GbE at sufficient distances (100m for OM3, 150m for OM4) required within data center environments.
Question 6: Which feature allows a data center network to carry multiple VLANs over a single physical link between switches?
- Port mirroring
- Link aggregation (LACP)
- VLAN trunking (IEEE 802.1Q) (Correct answer)
- Flow control (IEEE 802.3x)
Correct answer: VLAN trunking (IEEE 802.1Q)
IEEE 802.1Q VLAN trunking tags Ethernet frames with a VLAN ID, allowing a single physical link to carry traffic for multiple VLANs simultaneously.
CDCP Network Infrastructure and Connectivity 1
Which network topology is most commonly used within a data center to provide redundancy and high availability?