Cisco Network Engineer Interview questions

Are you looking for job as a network engineer/network administrator? Or are you thinking to leave your current position for a new job as a network engineer/administrator with a new company in a routed LAN/WAN environment?

If you answered yes to either of those questions, then this article is for you and any of described technologies and questions may be asked of you during the interview!

Network Engineer is a higher-level position, often with a “junior” or “senior” prefix. The major responsibility of a network engineer is to determine “how to implement technologies” in a routed LAN/WAN environment. They design and implement both the hardware and software technologies needed for a computer network. They have high-level technical skills in local area networks (LANs) or wide area networks (WANs).

Network Administrator is responsible for the smooth, efficient, and secure operation of computer networks. In general, they configure and administer existing networks rather than designing networks from the beginning. They play a very challenging role in a routed LAN/WAN environment, including customization of the network as per the organization’s needs, such as adding software and hardware, performance monitoring, troubleshooting, logging errors, backing up and restoring data, assigning permissions to users, and helping users with network issues.

Before facing any Interview for network engineer/administrator position, make sure that you have enough knowledge on below technologies.

General network concepts:

• Data communication and transmission techniques
• Fundamentals of OSI and TCP/IP model
• Router’s basic operations (startup, NVRAM, flash/IOS backup and recovery)

IP addressing and summarization:

• IP address classes
• Classful and classless IP addresses
• IP subnetting
• Understating wild card masks
• CIDR, FLSM, VLSM
• IPv6 fundamentals

Routing:

RIP

• Difference between RIPv1, RIPv2 and RIPng
• Passive Interface
• RIP Timers
• RIP AD and Multicast Address
• Split Horizon and Route Poisoning

EIGRP

• Auto and Manual Summarization
• Neighborship Conditions
• Split Horizon
• Authentication
• EIGRP Stub Routing and Stuck in Active
• Equal and Unequal Load Balancing
• EIGRP ADs and Multicast Address

OSPF

• OSPF Area Types
• OSPF Neighborship Conditions
• Concepts of ABR and ASBR Router
• DR/BDR Fundamentals and Election
• OSPF Times and Authentications
• OSPF Summarizations (Inter-Area, External, and Default Info Originate)
• OSPF AD and Multicast Addresses
• OSPF Network and LSA Types

BGP

• BGP Fundamentals – Why and When to Use BGP?
• BGP States and Message Types
• BGP Neighborship Conditions
• iBGP and eBGP
• BGP Summarization
• Use of Update Source, eBGP-Multi-Hop, Next-Hop-Self Commands
• BGP Path Attributes
• BGP Synchronization and Split-Horizon Rule
• BGP Address Families
• BGP Communities

MPLS

• MPLS Fundamentals – IP CEF, LIB, LFIB
• LDP and TDP
• P, PE and CE Routers
• PUSH, POP, SWAP Functions
• PHP – Penultimate Hop Popping
• BGP – VPN
• MPLS over ATM /Frame Relay

QoS

• QoS Models and Tools
• Difference between L2 and L3 Queues
• Characteristics of CoS, ToS, IPP, DSCP AF and EF
• Class Maps and Policy Maps

Route Filtering

• Access-List Fundamentals
• Route-Maps
• Prefix-Lists
• Distribute-Lists
• Filter-Lists

IP Services and Network Securities

• First-Hop Redundancy Protocols (HSRP, VRRP, GLBP)
• Network Address Translation (Static, Dynamic, PAT)
• Network Time Protocols, Syslog Server, SNMP
• Basics of VPNs (IPsec, Site to Site, DMVPN, Remote VPN)
• IP Multicast Routing (IGMP, PIM SM/DM, MSDP)
• Policy-Based Routing
• IP SLA

My Best Questions for an Interview of Network Engineer/Network Administrator: All of the questions below are very common and must be prepared for before facing any interview for the data-WAN environment.

1. What is a router? Or define the basic requirements of a router?

Answer: A router is a layer 3 network device used to establish communication between different networks. Basic roles performed by a router are:

• Inter-network communication
• Best path selection
• Packet forwarding
• Packet filtering

2. What is the use of routing? or Why we use routing?

Answer: By default, a router provides inter-network communication only for directly connected networks. To establish communication between indirectly connected networks, we require ROUTING. We can use static or dynamic (IGP or EGP) routing, according to topology requirement.