500 Networking Interview questions for Routers , Firewall , VPN

·        Networking Basics

·         Can you define protocol?

·         Can you explain the concept of OSI layer?

·         Can you explain the different layers in OSI model?

·          Can you explain Application layer in OSI model?

·          Can you explain Presentation layer in OSI model?

·          Is it compulsory that compression, encryption and translation functions will be used during communication?

·          Can you explain Session layer in OSI model?

·          What's the concept of Simplex, Half Duplex and Full Duplex dialogs?

·          What are the different types of dialogs in Session layer?

·          Can you explain Transport layer in OSI model?

·          Can you explain the concept of Congestion?

·          Can you explain Network Layer?

·          Can you explain Data link Layer?

·          Can you explain the Physical layer?

·          Can you explain what an IP address is?

·          How to convert Decimal to Binary?

·          How many IP addresses can come in IPV4?

·          Can you explain the concept of Unicast IP address?

·          Can you explain the concept of IP multicasting or multicast IP
address?

·          How many different types of subnet classful networks are present?

·          What are the IP address ranges for public and private IP address?

·          Why do we need class and how many different types of class exists?

·          How are the IP addresses distributed between different classes?

·          Can you explain what is classful IP addressing?

·          Can you explain the concept of subnetting?

·          What are the advantages of using subneting?

·           If the host has the subnet ID why do we need a subnet mask?

·           How is network address calculated from the subnet?

·          What is the advantage of using classless addressing over classful
  addressing scheme?

·          Can you explain the concept of CIDR?

·          Twist :- Can you explain superneting ?

·          Can you explain concept of custom subneting?

·          What is the implication of increasing and decreasing subnet Bits?

·           Why do we need to subtract two from number of hosts?

·          Can you explain the concept of VLSM?

·          Can you explain IP protocol?

·       Routers

·        Can you explain the concept of DPU, Segments, Datagram, Frame and
packet?

·        What is IP datagram fragmentation and MTU?

·        Can you explain in detail with example how data fragmentation works?

·         Larger the IP datagram less the overhead, is it true or false?

·        What is the minimum size of MTU bytes?

·        Can you explain how optimal MTU size is calculated?

·        How does the IP message finally reassemble?

·        Can you explain the concept of Repeaters, Hubs, Bridges, Switches and
Routers?

·        On what layers do router , switched , bridges and hubs operate ?

·        Can you explain the concept of Layer 3 switches?

·        what are CSU, DSU and TSU?

·        what are the basic components of the router?

·        Can you explain the WAN and LAN Interface in Routers?

·        What are DB-15, DB-60 and RJ-45 in CISCO routers?

·        Can you explain the concept of TTL?

·        What is the concept of ICMP packets?

·        Which operating system does CISCO have?

·        Can you explain the concept of NAT?

·        How is NAT implemented?

·        Can you explain how actually NAT works?

·        why does collision occur in HUBS and repeaters?

·        Can you explain the concept of Collision domain?

·        What is the concept of routing tables?

·        what is the use of route print?

·        Can you explain how in detail how routing table looks like?

·        How can you see route tables on the router?

·        Can you explain the concept of static and dynamic routing?

·        When to use Static routes and dynamic routes?

·        How do you configure static routes on a router?

·        Can you explain static default routes?

·        What is the advantage of using Static default routes?

·        Why do workstations have route tables?

·        

·        What is the concept of gateway of last resort?

·        Can you explain the concept of routing protocol?

·        What activities does routing protocol perform?

·        What metrics are used by routing protocols to determine the best path?

·        Can you explain what is interior and exterior routing protocols?

·        Can you explain the concept of intradomain and interdomain routing protocols?

·        Can you explain the concept of internetwork and intranetwork routing protocols?

·        Which method does routing protocol use to determine shortest path?

·        What is distance vector routing protocol?

·        How do router share information in Distance Vector routing?

·        What is the main issue with routing by rumor?

·        Can you explain the count-to-infinity problem in distance vector?

·        How is metric or the cost calculated for Distance Vector routing protocol?

·        What is the main issue with hop count metric issue?

·        Can you explain how Link-State routing protocols work?

·        Can you explain the concept of broad cast and multi-cast?

·        Can you tell which protocols lie in Distance vector and which in Link- State?

·        What's the difference between distance vector and link-state protocol?

·        Can you explain difference between Single path and Multipath?

·        Can you explain route summarization?

·        How are the series of IP combined in to one route path in route summarization?

·        Can you explain RIP protocol?

·        How is route table populated by RIP protocol?

·        Can you explain convergence in networks?

·        Can you explain RIP timers in detail?

·        Can you explain routing loop issue in RIP protocol?

·        How do we avoid routing loop issue in RIP?

·        In RIP why do we have HOP count of 15?

·        How do we disable auto-summarization in RIP?

·        Can you explain IGRP?

·        How does IGRP work?

·        How many timers does IGRP have?

·        How does IGRP calculate metric?

·        Can multiple instance of IGRP run on one physical router?

·        How is load balancing done in IGRP?

·        What's the command to configure IGRP?

·        Can you explain EIGRP?

·        What does neighbor terminology mean in EIGRP?

·        What are different types of packets in EIGRP?

·        How does EIGRP protocol update route information to its neighbors?

·        What is the concept of successor in EIGRP?

·        What is DUAL in EIGRP?

·        Can you explain reported distance (RD), feasibility distance (FD) and

·       Feasibility condition (FC)?

·        Can you explain the concept of successor and feasible successor?

·        Can you explain passive and active route states?

·        What is SIA or stuck in active?

·        How do packets and timers in EIGRP work?

·        What are the different tables used in EIGRP?

·        Can you explain EIGRP metrics?

·        Can you explain how EIGRP finds its successor and feasible successor?

·        Can you explain Active and Passive route?

·        Can you explain OSPF?

·        How does OSPF populate route table?

·        What are the different tables in OSPF?

·        Can you explain different areas in OSPF?

·        Can you explain different router types in OSPF?

·        Can you explain Designated Router and Backup designated router?

·        Can you explain different router states in OSPF?

·        Can you explain different OSPF packet types?

·        What are the different types of OSPF timers?

·        How SPF algorithm does the route determination?

·        Can you explain autonomous system?

·        What are different types of dynamic protocols?

·        Can you explain autonomous numbers in EGP?

·        What is BGP?

·        What is the concept of BGP speakers and Peers?

·        What is EBGP and IBGP?

·        What is RIB?

·        Can you explain the concept of BGP confederations?

·        What are BGP path attributes?

·        What is the concept of NLRI?

·        How are routing neighbors discovered in BGP?

·        Can you explain how BGP does the decision process?

·        What is the concept of redistribution?

·        Can you explain the concept of one way redistribution and mutual ?

·        How does metric translation takes place in redistributing routes?

·        Firewall

·         Can you define what a FIREWALL is?

·         What are the different types of firewalls?

·         Can you explain packet filtering firewall?

·         Can you explain circuit level gateway?

·         Can you explain stateful inspection?

·         What is Application Gateway?

·         Is NAT a firewall?

·         Are personal firewall actually firewalls?

·         Can you explain the concept of demilitarized zone?

·         What is the meaning of bastion host?

·         What are the different types of firewall architectures?

·         Can you explain dual home architecture?

·         Can you explain screened host architecture?

·         Can you explain screened subnet architecture?

·         What is the use of perimeter area?

·         What is IP spoofing and how can it be prevented?

·         VPN

·          Can you explain the difference between trusted and untrusted networks?

·          Can you define in short what VPN is?

·          What are the different types of VPN?

·          What requirements should a VPN fulfill?

·          How many ways are there to implement VPN architecture?

·          What are the different ways authentication mechanism in VPN?

·          Can you explain the basic of encryption in VPN?

·          what's the difference between Symmetric and Asymmetric cryptosystem?

·          what are the different symmetric algorithms?

·          What are the disadvantages of symmetric algorithms?

·          what are the different asymmetric algorithms?

·          Can you explain different components in PKI?

·          What is a digital certificate?

·          Can you explain tunneling?

·          what is the concept of HA and FA in VPN tunneling?

·          Can you explain VPN tunneled packet in detail?

·          Can you explain voluntary and compulsory tunnels?

·          Can you explain static and dynamic tunnels?

·          Can you explain encapsulating, carrier and passenger protocol?

·          On which layer does L2F, PPTP and L2TP operate?

·          Can you explain PPP protocol?

·           Can you explain PPP link process step by step?

·          Can you explain PPP packet format?

·          How does PPP use LCP for link control?

·          Can you explain PPTP (Point-to-Point Tunneling Protocol)?

·          What is GRE in PPTP?

·          How does PPTP encapsulate data?

·          Can you explain CHAP?

·          Can you explain PAP?

·         what does PPTP use for encryption and authentication?

·          What is a L2F protocol?

·          Can you explain the broader steps of how L2F establishes the tunnel?

·          Can you explain how L2F data tunneling process works?

·          How do we do encryption and authentication in L2F?

·          Can you explain L2TP?

·          Can you define LAC and LNS?

·          How does L2TP process?

·          How do we do encryption and authentication in L2TP?

·          Can you explain what IPSec is?

·          Can you give an overview of various components in IPSec?

·          In IPSec what is SAD, SPD and SA's?

·          Can you explain in a generic manner the packet of IPSec?

·          Can you describe the Authentication Header (AH) Protocol?

·           what is ESP (Encapsulating Security Payload)?

·          What is Transport and Tunnel mode?

·          Can you explain IKE (Internet Key Exchange)?

·          Can you explain IKE phases?

·          Can you explain IKE modes?

·          Can you explain transport and tunnel mode in detail with datagram packets?

·         Protocols and other questions

·         What is NetBIOS protocol?

·         Can you explain what the use of IGMP Protocol is?

·         What are the different types of host in multicasting?

·         Can you explain Ping and Tracert?

·         How do you continuously ping an IP Address?

·         How does Tracert actually work?

·         what is the use of RTP and RTCP Protocol?

·         Can you explain RTP in Detail?

·         Can you explain RTP multiplexing in detail?

·         Can you explain format of RTP and RTCP packets?

·         Can you explain RSVP?

·         Can you explain in detail how RSVP actually works?

·         Can you explain RPC (Remote Procedure Calls)?

·         Can you explain the RPC and Client server Architecture?

·         Can you explain TCP IP Protocol?

·         Can you explain the architecture of TCP IP Protocol?

·         Can you explain TCP header in detail?

·         Can you explain IP protocol?

·         Can you explain the concept of CDMA?

·         Can you explain the concept of DHCP?

·         How does DHCP work?

·         How can we configure DHCP?

·         What is DNS?

·         How do we control USB through a network?

·         What is the difference between Windows 2000 and Windows 2003?

·         What is a difference between a domain and workgroup?