Networking Flashcards
Enterprise Ethernet Datacenter Switching/Routing (L1-L3) (19 cards)
Can you explain the role of the Physical Layer (Layer 1) in networking and give examples of equipment used at this layer?
The Physical Layer is responsible for the transmission and reception of raw bit streams over a physical medium. Examples of equipment include copper ethernet cables, fiber optic cables, and ethernet hubs.
What are some common issues that can occur at the Physical Layer, and how would you troubleshoot them?
Common issues include cable faults, incorrect cable types, and signal interference. Troubleshooting steps may involve checking cable connections, using cable testers, and ensuring proper cable types and lengths.
Describe the function of a Layer 2 switch and how it differs from a hub.
A Layer 2 switch operates at the Data Link Layer and uses MAC addresses to forward data to specific ports, whereas a hub broadcasts data to all ports without any filtering or addressing.
What is a VLAN, and how does it improve network performance and security?
A VLAN (Virtual LAN) segments a network into different broadcast domains, reducing congestion and enhancing security by isolating traffic between different segments.
How does a Layer 3 switch differ from a Layer 2 switch, and when would you use one over the other?
A Layer 3 switch can perform routing functions, allowing communication between different VLANs or subnets, whereas a Layer 2 switch cannot. Layer 3 switches are used when inter-VLAN routing is needed.
Can you explain the concept of routing and how it is implemented in a Layer 3 switch?
Routing is the process of selecting paths in a network along which to send data packets. A Layer 3 switch uses IP addresses to make routing decisions and forward packets between different VLANs or subnets.
What is BGP, and why is it important for Internet routing?
BGP (Border Gateway Protocol) is the protocol used to exchange routing information between autonomous systems on the Internet. It is crucial for determining the most efficient paths for data to travel across the Internet.
Describe a scenario where a misconfiguration in BGP could lead to significant network issues.
A misconfiguration in BGP, such as incorrect route advertisement, can lead to traffic being misrouted or dropped, causing network outages or degraded performance. Examples include the 2008 incident where a Pakistani ISP accidentally blocked access to YouTube globally.
What is DHCP Relay, and why is it used in large networks?
DHCP Relay allows DHCP clients to communicate with DHCP servers that are not on the same local subnet. It is used to centralize DHCP services and manage IP address allocation efficiently across multiple subnets.
How would you configure a DHCP Relay on a network switch?
Configuration involves enabling the DHCP Relay feature on the switch and specifying the IP address of the DHCP server to which requests should be forwarded. This typically requires access to the switch’s configuration interface and appropriate administrative privileges.
What is ECMP, and how does it benefit network performance?
ECMP (Equal-Cost Multi-Path Routing) allows multiple paths of equal cost to be used for routing traffic, improving bandwidth utilization and load balancing across the network.
Can you discuss the potential challenges of implementing ECMP in a network?
Challenges include ensuring consistent packet delivery order, which is critical for certain types of traffic like VoIP. Proper configuration and monitoring are required to avoid issues such as packet reordering and uneven load distribution.
Can you explain the OSI model and its significance in networking?
The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and implement network protocols in seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer serves a specific function and interacts with the layers directly above and below it, facilitating standardized communication across diverse systems.
What is the difference between a router and a switch?
A router operates at the Network Layer (Layer 3) and is used to connect multiple networks, directing data packets based on IP addresses. A switch operates at the Data Link Layer (Layer 2) and is used to connect devices within the same network, forwarding data based on MAC addresses.
What is DNS and how does it work?
DNS (Domain Name System) is a hierarchical and decentralized naming system used to translate human-readable domain names (like www.example.com) into IP addresses (like 192.0.2.1). It involves multiple components, including DNS servers and resolvers, to facilitate this translation process.
Describe a situation where you had to troubleshoot a network issue. What steps did you take?
The candidate should describe a specific incident, outlining the problem, the diagnostic steps taken (such as checking physical connections, using network diagnostic tools like ping and traceroute, examining logs), the resolution, and any preventive measures implemented to avoid future occurrences.
How do you approach testing a new network setup to ensure it meets performance and reliability standards?
The candidate should discuss a systematic approach, including defining test cases, using network simulation tools, conducting stress tests, measuring latency and throughput, verifying redundancy and failover mechanisms, and documenting results for analysis and improvement.
What tools and techniques do you use for network performance monitoring and troubleshooting?
The candidate should mention tools like Wireshark for packet analysis, SNMP-based monitoring tools (e.g., Nagios, Zabbix), network performance testing tools (e.g., iPerf), and techniques such as baseline performance measurement, anomaly detection, and root cause analysis.
Explain how you would test the implementation of BGP in a network environment.
The candidate should describe configuring BGP peers, verifying route advertisements and acceptances, using tools like BGP Looking Glass for external route validation, simulating failover scenarios, and ensuring proper route policies and filters are in place to prevent route leaks and optimize path selection.
