Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About Airtel hiring for CCNA roles
Bharti Airtel is an Indian telecom company providing mobile, broadband, DTH, enterprise connectivity and digital services such as Airtel Thanks and Airtel Payments Bank. Its digital and analytics teams work on network data, customer analytics and app development. It hires for software engineers, testers, network engineers and data professionals.
For CCNA roles, this Airtel practice set focuses most on STP and EtherChannel (7), Wireless and Automation (7), Network Fundamentals (4), IP Services (4). It has 9 easy, 17 medium, 4 hard questions, so you can start easy and work up to the harder ones.
Company type
Telecom
Headquarters
New Delhi, India
Main India offices
Gurugram, Bengaluru, Mumbai, Pune
Airtel CCNA interview process
Online assessment (aptitude + technical)
Technical interview
Managerial round
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
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01
An EtherChannel shows members in suspended state. What do you check?
Suspended (s) usually means a configuration mismatch between members or with the far end. I compare speed, duplex, trunk mode, native VLAN and allowed VLANs on each member and the port-channel with show run interface, check LACP modes on both sides, and look at logs. I fix the config on the port-channel, then shut and no shut members so they rejoin. show etherchannel summary should show P flags.
02
How would you represent an interface configuration in JSON and YAML?
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
03
Explain root port, designated port and blocked port.
Every non-root switch picks one root port, its best path to the root based on lowest root path cost, then lowest sender bridge ID, then lowest sender port ID. On each segment, the switch with the best path becomes the designated port and forwards. Every remaining port becomes non-designated and blocks. All ports on the root bridge are designated.
04
What is a REST API and which HTTP methods map to CRUD?
A REST API exposes resources at URLs and is stateless, usually with JSON payloads over HTTPS. CRUD maps to HTTP verbs: POST creates, GET reads, PUT replaces or PATCH partly updates, and DELETE removes. Responses use status codes such as 200 OK, 201 Created, 401 Unauthorized, 404 Not Found and 500 Server Error. Controllers expose northbound REST APIs for automation.
05
What are the default STP path costs for common link speeds?
With short (802.1D revised) costs: 10 Mbps is 100, 100 Mbps is 19, 1 Gbps is 4 and 10 Gbps is 2. With the long pathcost method, 1 Gbps is 20000 and 10 Gbps is 2000, which distinguishes higher speeds. Root path cost is the sum of costs on ports toward the root, and the lowest total wins when choosing root ports.
06
A broadcast storm brought the network down after someone connected a cable between two wall ports. How do you prevent this?
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.
07
How do you configure SSH access on a switch or router?
SSH needs a hostname, domain name, RSA keys, a local user and VTY lines restricted to SSH.
hostname R1
ip domain-name lab.local
crypto key generate rsa modulus 2048
ip ssh version 2
username admin privilege 15 secret Adm1nPass
line vty 0 4
login local
transport input ssh
08
How do you back up and restore a device configuration?
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.
The TCP/IP model has four or five layers. Its Application layer covers OSI layers 5 to 7, Transport maps to Layer 4, Internet maps to Layer 3, and Network Access (or Link plus Physical) covers layers 1 and 2. CCNA uses the five-layer version. Real protocols such as HTTP, TCP and IP are defined by the TCP/IP suite, so it is the practical model.
10
Your manager wants to stop configuring 200 switches manually. What would you propose?
I would start with a source of truth for devices and variables, then use Ansible playbooks with Jinja2 templates to generate and push standard configs over SSH, keeping them in Git with peer review. A controller such as Catalyst Center could handle day-0 provisioning and compliance. I would start with read-only tasks like backups and audits, then move to small, tested change automation.
The underlay is the physical IP network of switches and routers that provides basic reachability, for example OSPF or IS-IS on routed links. The overlay is a virtual network built on top using tunnels such as VXLAN, so logical segments can stretch across the fabric independent of physical topology. SD-Access and SD-WAN use this model, with a fabric controlling the overlay.
12
Users complain Wi-Fi is slow in a conference room with 60 people. What do you check and fix?
This is usually a capacity, not a coverage, issue. I check client count per AP and channel utilisation on the controller. Fixes include adding APs with lower transmit power, steering clients to 5 or 6 GHz with band steering, disabling low data rates such as 1, 2 and 5.5 Mbps, using 20 or 40 MHz channels in dense areas, and limiting per-client bandwidth on the SSID.
13
A server team reports that a link between two switches is up but traffic is dropping intermittently. What do you check?
I check show interfaces on both ends for input errors, CRC, runts, giants, output drops and resets. Output drops suggest congestion, so I look at utilisation and QoS. CRC errors suggest a bad cable, dirty fiber or faulty SFP, so I check optical levels with show interfaces transceiver. I also confirm both sides agree on speed and duplex and that the MTU matches.
RFC 3021 allows /31 on point-to-point links because there is no need for network and broadcast addresses when only two devices exist. A /31 gives exactly two usable addresses, saving half the space of a /30. It is common on ISP and data center fabric links. Both ends must support it; on IOS you simply configure ip address 10.0.0.0 255.255.255.254.
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.
16
What is the difference between autonomous APs, controller-based APs and cloud-managed APs?
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.
Configure the same group and virtual IP on both switches, with higher priority on the active one.
interface vlan 10
ip address 192.168.10.2 255.255.255.0
standby version 2
standby 10 ip 192.168.10.1
standby 10 priority 110
standby 10 preempt
show standby brief
Hosts use 192.168.10.1 as their gateway.
18
A PC in VLAN 20 cannot reach a PC in VLAN 30. What do you check?
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.
TCP is connection-oriented: it uses a three-way handshake, sequence numbers, acknowledgements, retransmission, windowing and flow control, so delivery is reliable and ordered. UDP is connectionless with an 8-byte header and no retransmission, so it is faster and lighter. HTTPS, SSH and SMTP use TCP; DNS queries, DHCP, SNMP, TFTP and voice or video RTP streams use UDP.
CoS is a 3-bit priority field in the 802.1Q tag, values 0 to 7, used only on Layer 2 trunks. DSCP is a 6-bit field in the IP header, values 0 to 63, which survives across routed hops. Common values: EF (46) for voice, AF41 (34) for video, CS3 (24) for call signalling and default (0) for best effort. Mark close to the source and trust markings only at controlled boundaries.
21
Find the network, broadcast and usable range for 172.16.45.200/21.
A /21 mask is 255.255.248.0, so the interesting octet is the third with block size 8. 45 falls in the block starting at 40 (40 to 47).
Network: 172.16.40.0
Broadcast: 172.16.47.255
Usable: 172.16.40.1 - 172.16.47.254
Hosts: 2^11 - 2 = 2046
Set priorities on the intended primary and secondary roots, then verify.
spanning-tree mode rapid-pvst
spanning-tree vlan 10,20 root primary
! on the backup switch
spanning-tree vlan 10,20 root secondary
show spanning-tree vlan 10
show spanning-tree root
show spanning-tree summary
Network Address Translation rewrites IP addresses as packets cross a router, usually private inside addresses to public outside ones. Static NAT maps one inside address to one public address, often for servers. Dynamic NAT maps from a pool. PAT, or NAT overload, maps many inside hosts to one public IP using unique source ports, and is what almost every office and home router uses.
Use one trunk link and a subinterface per VLAN with 802.1Q encapsulation.
interface GigabitEthernet0/0
no shutdown
interface GigabitEthernet0/0.10
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
interface GigabitEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.20.1 255.255.255.0
The switch port facing the router must be a trunk.
25
A Python script gets 401 errors when calling a controller REST API. What do you check?
401 Unauthorized means authentication failed. I check the username and password or API key, whether a token must first be requested from an auth endpoint and sent in a header like X-Auth-Token, whether the token expired, and the exact header name and format. I test the same call with curl or an API client to separate script bugs from credential issues.
Mark interfaces, match inside hosts with an ACL and overload the outside interface.
interface GigabitEthernet0/1
ip nat inside
interface GigabitEthernet0/0
ip nat outside
access-list 1 permit 192.168.0.0 0.0.255.255
ip nat inside source list 1 interface GigabitEthernet0/0 overload
show ip nat translations
Member interfaces must have the same speed and duplex, the same mode (access or trunk), the same access VLAN or the same native and allowed VLAN list on trunks, and compatible negotiation modes. Mismatched settings put members into suspended state. Configure settings on the port-channel interface so they are pushed to members, and verify with show etherchannel summary.
28
How do you create a VLAN and assign an access port?
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
The router ID is a 32-bit value chosen in this order: manually configured router-id, then the highest IP on an up loopback interface, then the highest IP on an up physical interface. It is chosen when the OSPF process starts, so changes need clear ip ospf process. Best practice is to set it manually so it is stable and easy to recognise in the database.
30
What is route summarization and how do you calculate a summary?
Summarization advertises one prefix that covers several contiguous networks, shrinking routing tables and hiding instability. Write the networks in binary and keep the common leading bits. For 10.1.4.0/24 to 10.1.7.0/24, the third octet values 4 to 7 share the first six bits (000001), so the summary is 10.1.4.0/22. Make sure the summary does not include networks that live elsewhere.
Tips to crack the Airtel CCNA interview
Learn telecom basics like ARPU, churn, 4G and 5G networks, and broadband rollout for case discussions.
Prepare analytics cases on reducing customer churn or improving network quality using data.
Read about Airtel's digital products like Airtel Thanks and Xstream, and its enterprise business Airtel Business.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; Airtel interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the Airtel CCNA interview?
Candidates usually go through 4 stages: Online assessment (aptitude + technical); Technical interview; Managerial round; HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the Airtel CCNA interview?
This practice set leans on STP and EtherChannel (7), Wireless and Automation (7), Network Fundamentals (4), IP Services (4). Revise those first, then practise explaining one or two of your own projects end to end, because most Airtel interviewers ask you to walk through real work.
Are these the exact questions asked at Airtel?
No. These are curated practice questions that match the skills and difficulty usually tested in telecom interviews like Airtel's. They are not a leaked or verified list of past questions.
Where does Airtel hire CCNA professionals in India?
Airtel has large teams in Gurugram, Bengaluru, Mumbai, Pune. Openings and locations change often, so check the Airtel careers page and filter by city and experience.