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CCNA Interview Questions in Chennai

36 practice questions with answers for CCNA interviews in Chennai.

CCNA jobs in Chennai

Chennai is a long-standing IT-services and SaaS hub along OMR, with strong demand for testing, data and support-engineering roles. Many companies here hire freshers in large batches and train them on the job.

Below are 36 questions that match the mix of service, product and domain employers hiring network support engineers in Chennai.

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01

What is a voice VLAN and how does it work?

Switching and VLANsMedium
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A voice VLAN lets an IP phone and a PC share one switch port while keeping their traffic separate. The port is an access port in the data VLAN, and the switch tells the phone through CDP or LLDP-MED to tag voice frames with the voice VLAN. This allows QoS priority for voice and separate addressing. Configure it with switchport voice vlan.
02

Guest Wi-Fi users must reach only the internet, not internal networks. How do you enforce it?

Network SecurityMedium
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Put guests in their own VLAN and subnet, ideally terminating on a firewall or a separate VRF. Apply an inbound extended ACL on the guest SVI that permits DHCP and DNS to the allowed servers, denies all RFC 1918 destinations, and then permits any to the internet. Enable client isolation on the wireless side and rate limit the guest SSID so it cannot consume the WAN.
03

What is 802.1Q tagging?

Switching and VLANsEasy
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802.1Q inserts a 4-byte tag after the source MAC in the Ethernet frame. The tag holds a 12-bit VLAN ID (1 to 4094 usable), 3 priority bits used by CoS for QoS, and a DEI bit. The tag is added when a frame leaves a trunk and removed at an access port. Older ISL encapsulation is obsolete; modern switches support only 802.1Q.
04

How do you configure port security with sticky MACs?

Network SecurityEasy
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Port security works on static access ports. interface GigabitEthernet1/0/10 switchport mode access switchport port-security switchport port-security maximum 2 switchport port-security mac-address sticky switchport port-security violation restrict show port-security interface Gi1/0/10
05

How do you restrict SSH access to devices from only the management subnet?

Network SecurityMedium
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Use a standard ACL on the VTY lines. ip access-list standard MGMT-ONLY permit 10.99.0.0 0.0.0.255 deny any log line vty 0 15 access-class MGMT-ONLY in transport input ssh exec-timeout 10 0 login block-for 120 attempts 3 within 60
06

How does DHCP snooping protect the network?

Network SecurityMedium
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DHCP snooping classifies ports as trusted (uplinks toward real DHCP servers) or untrusted (user ports). Server messages such as Offer and Ack arriving on untrusted ports are dropped, which stops rogue DHCP servers. It also builds a binding table of MAC, IP, VLAN and port, which Dynamic ARP Inspection and IP Source Guard use. Rate limits on untrusted ports prevent DHCP starvation.
07

How would you represent an interface configuration in JSON and YAML?

Wireless and AutomationEasy
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The same data in both formats. JSON: { "interface": "GigabitEthernet0/1", "enabled": true, "ipv4": ["192.168.1.1/24"] } YAML: interface: GigabitEthernet0/1 enabled: true ipv4: - 192.168.1.1/24
08

How do you create a VLAN and assign an access port?

Switching and VLANsEasy
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Create the VLAN, name it, and set the port mode and VLAN. vlan 20 name SALES interface GigabitEthernet1/0/5 switchport mode access switchport access vlan 20 switchport voice vlan 150 spanning-tree portfast show vlan brief
09

How do you stay updated on network security threats?

Network SecurityEasy
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Situation: as a fresher I realised many interview questions asked about recent attacks. Task: build a habit of learning. Action: I follow vendor security advisories, CERT-In alerts and a few security newsletters, practise in a home lab with packet captures, and read the release notes of devices we use. Result: I can explain current threats in interviews and suggested patching a vulnerable IOS version in my internship.
10

What are SSID, BSSID and ESS?

Wireless and AutomationEasy
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The SSID is the network name users see. The BSSID is the MAC address of the access point radio serving a BSS, the basic service set of one AP and its clients. An ESS is multiple BSSs sharing the same SSID connected by a wired distribution system, so clients can roam between APs. Each AP can broadcast several SSIDs, each with its own BSSID.
11

How do you configure an LACP EtherChannel trunk?

STP and EtherChannelMedium
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Put members in a channel group with mode active, then configure the port-channel. interface range GigabitEthernet1/0/47 - 48 channel-group 1 mode active interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10,20,99 port-channel load-balance src-dst-ip show etherchannel summary
12

A broadcast storm brought the network down after someone connected a cable between two wall ports. How do you prevent this?

STP and EtherChannelMedium
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Two wall ports patched to the same switch formed a loop. To stop it now, I find the port with rising broadcast counters and shut it. To prevent repeats, enable PortFast with BPDU Guard on all access ports, keep Rapid PVST+ running everywhere, add storm-control broadcast thresholds on access ports and enable errdisable recovery with a sensible interval.
13

Explain the TCP three-way handshake.

Network FundamentalsEasy
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The client sends a SYN with an initial sequence number. The server replies with SYN-ACK, acknowledging the client sequence and sending its own. The client sends an ACK and the session is established. Closing uses FIN and ACK from each side. A firewall that sees repeated SYNs without the final ACK may be looking at a SYN flood attack.
14

How do you make an access switch port a routed port on a Layer 3 switch?

Switching and VLANsHard
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A routed port behaves like a router interface and does not belong to any VLAN. interface GigabitEthernet1/0/1 no switchport ip address 10.0.0.1 255.255.255.252 no shutdown Routed uplinks between distribution and core avoid spanning tree on those links and allow fast routing convergence with ECMP.
15

After adding a new VLAN, users on one access switch cannot use it but others can. Why?

Switching and VLANsMedium
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The most likely cause is the trunk to that switch does not allow the new VLAN, because someone configured an explicit allowed list. Check show interfaces trunk and add it with switchport trunk allowed vlan add 50, not without add, which would replace the list. Also confirm the VLAN exists on that switch with show vlan brief, especially if VTP is transparent.
16

How would you influence which port becomes the root port on a switch?

STP and EtherChannelHard
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The root port is chosen by lowest cost, then sender bridge ID, then sender port ID. To prefer a link I lower its cost. interface GigabitEthernet1/0/49 spanning-tree vlan 10 cost 2 On the upstream switch you can change port priority instead. interface GigabitEthernet1/0/1 spanning-tree vlan 10 port-priority 64
17

Two hosts are in the same VLAN but one has mask /24 and the other /25. What problems may occur?

IP Addressing and SubnettingMedium
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Each host decides local or remote using its own mask. With 192.168.1.10/24 and 192.168.1.200/25, the first thinks .200 is local and ARPs directly, but the second sees .10 as remote and sends replies to its gateway. Traffic can become one-way or asymmetric and may break completely if the gateway does not route it back. Fix the mask so both match the design.
18

Describe a situation where you had to explain a technical issue to a non-technical manager.

Routing and OSPFMedium
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Situation: a routing loop during a carrier change caused a two-hour outage and the operations head wanted an explanation. Task: explain cause and prevention simply. Action: I used a road map analogy, explained that two routers kept sending traffic to each other, showed the timeline and our fix, and listed three prevention steps with dates. Result: management approved a proper change review board, and trust in our team improved.
19

What is EtherChannel and its benefits?

STP and EtherChannelEasy
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EtherChannel bundles 2 to 8 physical links into one logical port-channel. STP sees it as one link, so all members forward instead of one being blocked. It adds bandwidth and redundancy, as one member failing does not drop the channel. Traffic is load-balanced per flow using a hash of MAC, IP or port fields, so a single flow still uses only one member link.
20

Compare LACP and PAgP.

STP and EtherChannelMedium
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LACP (802.3ad, now 802.1AX) is the open standard with modes active and passive; at least one side must be active. PAgP is proprietary with modes desirable and auto; at least one side must be desirable. Mode on forces the channel with no negotiation, which can cause loops if the other side is not configured. LACP is preferred because it works with servers, firewalls and other vendors.
21

How do you configure IPv4 static and default routes?

Routing and OSPFEasy
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Use a next-hop IP, an exit interface, or both. ip route 10.2.0.0 255.255.0.0 192.168.12.2 ip route 0.0.0.0 0.0.0.0 203.0.113.1 ! floating backup with AD 200 ip route 0.0.0.0 0.0.0.0 198.51.100.1 200 ! IPv6 ipv6 route ::/0 2001:db8:12::2 show ip route static
22

What are the WLC port and interface types?

Wireless and AutomationHard
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Physical ports include service ports for out-of-band management, distribution system ports that connect to the switch as trunks, and redundancy ports for HA. Logical interfaces include the management interface used for CAPWAP and admin access, dynamic interfaces that map WLANs to VLANs, and a virtual interface used for web auth and DHCP relay. A LAG bundles distribution ports.
23

How does a router choose the best route to a destination?

Routing and OSPFEasy
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First it uses longest prefix match: the most specific matching prefix wins, so 10.1.1.0/24 beats 10.1.0.0/16. If the same prefix comes from different sources, the lowest administrative distance wins. If the same protocol offers several paths, the lowest metric wins, and equal metrics can be load-balanced with ECMP. Only the winners are installed in the routing table.
24

A PC in VLAN 20 cannot reach a PC in VLAN 30. What do you check?

Switching and VLANsMedium
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First I check each PC has the correct IP, mask and gateway for its VLAN. Then I confirm the switch ports are in the right VLANs with show vlan brief, and that the trunk to the Layer 3 device allows both VLANs using show interfaces trunk. On the Layer 3 device I check the SVIs or subinterfaces are up and have the right IPs, and that no ACL blocks the traffic.
25

Explain the main IPv6 address types.

IP Addressing and SubnettingMedium
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Global unicast (2000::/3) is publicly routable. Unique local (fc00::/7, in practice fd00::/8) is like private IPv4. Link-local (fe80::/10) is auto-created on every IPv6 interface and used for neighbour discovery and routing next hops. Multicast is ff00::/8, for example ff02::1 all nodes and ff02::2 all routers. Anycast is a unicast address shared by several devices. IPv6 has no broadcast.
26

How do you call a REST API from Python and parse the JSON?

Wireless and AutomationHard
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Use the requests library and convert the reply to a dictionary. import requests url = 'https://controller.example.local/api/v1/network-device' headers = {'X-Auth-Token': token, 'Accept': 'application/json'} r = requests.get(url, headers=headers, timeout=10) r.raise_for_status() for dev in r.json()['response']: print(dev['hostname'], dev['managementIpAddress'])
27

How do you configure a router as a DHCP relay and verify it?

IP ServicesMedium
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Add the helper address on the client-facing interface. interface vlan 20 ip helper-address 10.0.0.50 show ip interface vlan 20 | include Helper debug ip dhcp server packet The helper also forwards some other UDP broadcasts such as TFTP and DNS by default; use no ip forward-protocol udp to limit them.
28

What is the difference between autonomous APs, controller-based APs and cloud-managed APs?

Wireless and AutomationMedium
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Autonomous APs are configured one by one and suit very small sites. Lightweight APs are managed by a Wireless LAN Controller using CAPWAP tunnels, which centralises configuration, RF management and roaming, and suits campuses. Cloud-managed APs are configured from a cloud dashboard, ideal for many branches. Split-MAC means real-time functions stay on the AP while management sits on the controller.
29

What is DTP and why should you disable it?

Switching and VLANsMedium
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Dynamic Trunking Protocol negotiates whether a link becomes a trunk. Modes are dynamic auto, dynamic desirable, trunk and access. Auto plus auto stays access, while desirable with auto or desirable forms a trunk. Attackers can use DTP to form a trunk and reach all VLANs, so best practice is to hard-code access or trunk and use switchport nonegotiate on trunks.
30

Compare WPA2 and WPA3 security.

Wireless and AutomationMedium
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WPA2 uses AES-CCMP; WPA2-Personal uses a pre-shared key that is vulnerable to offline dictionary attacks, and WPA2-Enterprise uses 802.1X with RADIUS. WPA3-Personal replaces PSK with SAE, which resists offline guessing and gives forward secrecy. WPA3-Enterprise offers a 192-bit mode. WPA3 requires protected management frames. Open networks can use OWE for encryption without passwords.
31

Explain password security best practices for network devices.

Network SecurityEasy
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Use enable secret, not enable password, so the hash is strong (type 8 or 9 on modern IOS). Create local users with secret, enforce minimum length with security passwords min-length, and use AAA with TACACS+ for central control. Disable Telnet, use SSH v2, set exec-timeout on lines, and add login block-for to slow brute force. Avoid type 7 passwords, which are easily reversed.
32

How do you back up and restore a device configuration?

IP ServicesMedium
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Copy the config to a server and back. copy running-config tftp://10.0.0.40/R1-backup.cfg copy running-config scp://admin@10.0.0.40/R1.cfg copy tftp://10.0.0.40/R1-backup.cfg running-config configure replace flash:R1-good.cfg archive path flash:R1-archive write-memory configure replace gives a clean rollback instead of merging.
33

How do you write and apply an extended named ACL?

Network SecurityMedium
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Allow web traffic from one subnet to a server and block the rest of that subnet. ip access-list extended WEB-ONLY 10 permit tcp 192.168.10.0 0.0.0.255 host 10.0.0.80 eq 443 20 deny ip 192.168.10.0 0.0.0.255 10.0.0.0 0.0.0.255 30 permit ip any any interface vlan 10 ip access-group WEB-ONLY in show access-lists WEB-ONLY
34

What is port security and what are its violation modes?

Network SecurityMedium
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Port security limits the MAC addresses allowed on an access port, either statically or by sticky learning. If an extra MAC appears, the violation mode acts: shutdown (default) err-disables the port, restrict drops the frames, logs and increments a counter, and protect silently drops frames. It stops MAC flooding and unauthorised devices on user ports.
35

Tell me about a time you had to learn a new technology quickly.

STP and EtherChannelMedium
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Situation: our team moved from PVST to MST for a data center with 600 VLANs, and I had not used MST. Task: be ready for the migration in two weeks. Action: I read the configuration guides, built the design in a GNS3 lab, broke it deliberately and wrote a step-by-step checklist. Result: the migration ran in one window without outage, and I ran a short knowledge session for the team.
36

How do you configure single-area OSPFv2?

Routing and OSPFMedium
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Set a router ID, enable OSPF on interfaces and make user ports passive. router ospf 1 router-id 1.1.1.1 auto-cost reference-bandwidth 100000 passive-interface GigabitEthernet0/1 network 10.0.12.0 0.0.0.3 area 0 network 192.168.1.0 0.0.0.255 area 0 default-information originate Or per interface: ip ospf 1 area 0

Companies with offices in Chennai (14)

IT services

TCS

CCNA interview questions

  • 30 questions
  • 4 rounds

Mumbai, Chennai, Pune +2

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IT services

Infosys

CCNA interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Mysuru, Pune +2

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IT services

Wipro

CCNA interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Hyderabad, Pune +2

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IT services

HCLTech

CCNA interview questions

  • 30 questions
  • 4 rounds

Noida, Chennai, Bengaluru +2

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IT services

Tech Mahindra

CCNA interview questions

  • 30 questions
  • 4 rounds

Pune, Hyderabad, Bengaluru +2

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IT services

Cognizant

CCNA interview questions

  • 30 questions
  • 4 rounds

Chennai, Bengaluru, Pune +2

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IT services

Capgemini

CCNA interview questions

  • 30 questions
  • 4 rounds

Mumbai, Bengaluru, Pune +2

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Hardware & semiconductors

Cisco

CCNA interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Pune, Chennai

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Telecom

Ericsson

CCNA interview questions

  • 30 questions
  • 4 rounds

Gurugram, Bengaluru, Chennai +2

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Telecom

Nokia

CCNA interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Chennai, Noida +1

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IT services

NTT DATA

CCNA interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Pune, Noida +2

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IT services

LTIMindtree

CCNA interview questions

  • 30 questions
  • 4 rounds

Mumbai, Pune, Bengaluru +2

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Banking & finance

HDFC Bank

CCNA interview questions

  • 30 questions
  • 4 rounds

Mumbai, Chennai, Bengaluru

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Product

Amazon

CCNA interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Hyderabad, Chennai +2

View questions

Frequently asked questions

Which companies hire CCNA professionals in Chennai?

Companies with large offices in Chennai include TCS, Infosys, Wipro, HCLTech, Tech Mahindra, Cognizant, Capgemini, Cisco, Ericsson, Nokia. Use their company pages below to practise employer-specific sets.

Are CCNA interviews in Chennai different from other cities?

The questions depend more on the company than the city. Chennai's mix of employers decides the style: Many companies here hire freshers in large batches and train them on the job

How do I find CCNA jobs in Chennai?

Shortlist companies with Chennai offices, keep your CV focused on CCNA projects, apply on company career pages and job portals with the Chennai filter, and practise the questions on this page before each interview.

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