36 practice questions with answers for CCNA interviews in Thiruvananthapuram.
CCNA jobs in Thiruvananthapuram
Thiruvananthapuram's Technopark is one of India's oldest IT parks, hosting IT-services, product and engineering-services companies. Data and testing teams here often work with global clients in finance, travel and healthcare.
Below are 36 questions that match the mix of service, product and domain employers hiring network support engineers in Thiruvananthapuram.
Solved for ThiruvananthapuramStart practicing
3 QUESTIONS FREESign up to unlock the full question bank and track your progress.Unlock every question and answer, then continue practising company-wise and package-wise.
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.
A switch reads the source MAC of each incoming frame and records it with the port in the MAC address table. For forwarding it looks up the destination MAC: a known unicast goes out one port, while unknown unicast, broadcast and most multicast frames are flooded in the VLAN. Entries age out after 300 seconds by default. Check with show mac address-table.
Areas limit how far detailed LSAs flood, so SPF runs on a smaller database and changes in one area do not force recalculation everywhere. Area 0 is the backbone and every other area must connect to it, directly or through a virtual link. Routers connecting areas are ABRs and can summarize routes between areas. Single-area OSPF is the focus of CCNA.
Quality of Service gives different treatment to traffic types when links are congested. Voice needs low delay (under 150 ms one way), low jitter (under 30 ms) and low loss (under 1 percent), while bulk file transfer can wait. QoS tools classify and mark traffic, queue it with priority queues for voice, and police or shape rates. Without congestion QoS has no effect.
05
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.
06
How do you prioritise when several tickets arrive at the same time?
Situation: on a night shift I got a core link down alert, two user tickets and a printer issue at once. Task: handle everything with minimum impact. Action: I prioritised by business impact, confirmed redundancy had taken over for the core link, raised a priority ticket with the carrier, then fixed the user tickets and logged the printer for morning. Result: no SLA was breached and the handover was clear.
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.
08
Traffic is taking a slow path because an old access switch became root bridge. How do you fix it?
The old switch has the lowest MAC with default priority, so it won the election. I set the core or distribution switch as root with spanning-tree vlan 1-4094 priority 4096, or root primary, and the secondary with 8192. I add Root Guard on distribution downlinks so access switches can never become root again. Then I verify with show spanning-tree root.
09
How do you make an access switch port a routed port on a Layer 3 switch?
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.
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.
11
A newly configured router interface rejects the IP 192.168.5.64/26. Why?
With a /26 the block size is 64, so 192.168.5.64 is the network address of the subnet .64 to .127 and cannot be assigned to a host or interface. IOS reports a bad mask or overlap error. Use a usable address such as 192.168.5.65 instead. Similarly .127 would be the broadcast. Always calculate the subnet boundary before configuring addresses.
Root Guard on a designated port puts it into root-inconsistent state if a superior BPDU arrives, protecting the planned root bridge, so it is used on distribution ports facing access switches. Loop Guard stops a non-designated port from becoming designated when BPDUs stop arriving, such as with a unidirectional fiber fault. UDLD complements Loop Guard by detecting one-way links.
13
What is AAA and the difference between TACACS+ and RADIUS?
AAA stands for Authentication (who you are), Authorization (what you can do) and Accounting (what you did). TACACS+ uses TCP 49, encrypts the whole payload and separates authentication from authorization, so it is preferred for device administration with per-command control. RADIUS uses UDP 1812 and 1813, encrypts only the password and is used for network access such as 802.1X and VPN.
14
Write a simple Ansible playbook that configures NTP on IOS devices.
A client asks its configured resolver, for example for www.example.com. If it is not cached, the resolver queries a root server, which refers it to the .com TLD server, which refers it to the authoritative server for example.com, which returns the A or AAAA record. The answer is cached for its TTL. DNS uses UDP 53 for most queries and TCP 53 for zone transfers and large replies.
16
What is SNMP and the differences between v2c and v3?
SNMP lets a manager poll devices for counters and receive traps or informs about events, using a MIB with OIDs. Polling uses UDP 161 and traps UDP 162. SNMPv2c uses a plain-text community string with no encryption. SNMPv3 adds user-based authentication and encryption with authPriv mode, so it is the version to use in production, especially on networks reachable from many teams.
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.
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.
DHCP Discover is a broadcast, and routers do not forward broadcasts, so a central DHCP server cannot hear clients on other subnets. A relay agent, configured with ip helper-address on the gateway interface, converts the broadcast into a unicast to the server and adds the gateway IP so the server picks the right scope. This lets one server serve many VLANs.
20
Compare Ansible, Puppet and Chef for network automation.
Ansible is agentless, uses SSH or APIs, writes playbooks in YAML and uses a push model, so it is the most popular for network devices. Puppet uses an agent, a declarative manifest language and a pull model. Chef uses Ruby-based recipes with an agent and pull model. Puppet and Chef are more common for servers. All support idempotent configuration management.
21
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.
22
What is EUI-64 and how is the interface ID generated?
EUI-64 builds a 64-bit interface ID from a 48-bit MAC. Split the MAC in half, insert FFFE in the middle and flip the seventh bit of the first byte. For MAC 0050.56AB.CDEF the ID becomes 0250:56FF:FEAB:CDEF. Routers can use ipv6 address 2001:db8:1::/64 eui-64. Hosts often prefer random privacy addresses instead, to avoid exposing the MAC.
Single-mode fiber has a small core (about 9 microns) and uses a laser, so it carries light over long distances, often 10 km or more. Multimode fiber has a larger core (50 or 62.5 microns), uses cheaper LED or VCSEL optics and suits shorter runs inside a building or data center, usually up to a few hundred metres at 10 Gbps. SFP modules must match the fiber type.
24
What is the difference between an access port and a trunk port?
An access port belongs to one VLAN and carries untagged frames, typically to PCs, printers or servers. A trunk port carries traffic for many VLANs between switches, routers or hypervisors, adding an 802.1Q tag to identify each frame's VLAN, except the native VLAN which is sent untagged. Access ports can also carry a separate voice VLAN for IP phones.
25
How are ACL entries processed and what is the implicit deny?
ACL entries are checked top-down and the first match decides permit or deny; later lines are ignored. Every ACL ends with an invisible deny any, so traffic that matches no line is dropped. Therefore specific entries must come before general ones, and an ACL with only deny statements blocks everything. Always add a permit for allowed traffic and test after applying.
26
Syslog timestamps from different devices do not match during an incident review. What do you fix?
Clocks are not synchronised. I configure all devices to use the same internal NTP servers with ntp server, set the timezone with clock timezone IST 5 30, add service timestamps log datetime msec localtime, and enable NTP authentication. Then I check show ntp associations and show ntp status to confirm synchronisation. This makes future incident timelines reliable.
27
How do you handle a change that must be done during a night window?
Situation: we had to migrate 30 access ports to new VLANs overnight. Task: finish with zero business impact. Action: I prepared configs in advance, got peer review, scheduled a rollback, informed the helpdesk and tested each floor with a laptop after changes. Result: the migration finished an hour early, morning tickets were zero, and the plan became our template for later VLAN changes.
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.
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
How do you approach working in a 24x7 network operations shift?
Situation: I joined a NOC that ran rotating shifts. Task: stay effective and keep handovers clean. Action: I followed runbooks, kept a shift log of every alert and action, raised early escalations for anything outside my scope and used quiet hours to lab new topics. Result: I handled shift incidents within SLA, earned positive feedback for clear handovers and was moved to the L2 team in a year.
31
How do you configure AAA with TACACS+ and a local fallback?
Define the server, then method lists with local as backup.
aaa new-model
tacacs server ISE1
address ipv4 10.0.0.60
key Tac@csKey1
aaa authentication login default group tacacs+ local
aaa authorization exec default group tacacs+ local
aaa accounting commands 15 default start-stop group tacacs+
username breakglass privilege 15 secret L0calOnly!
32
What is the MAC address table and what happens when it is full?
The MAC address table, stored in CAM, maps MAC addresses to ports and VLANs. When it fills, as in a MAC flooding attack, new addresses cannot be learned and the switch floods unknown unicast frames out of all ports in the VLAN, which lets an attacker sniff traffic. Port security limiting MACs per port prevents this.
Switches exchange BPDUs and the one with the lowest bridge ID becomes root. The bridge ID is the priority (default 32768 plus the VLAN number in PVST) followed by the MAC address, so if priorities tie, the lowest MAC wins. Because the oldest switch often has the lowest MAC, you should set priority manually, for example spanning-tree vlan 10 root primary on the core.
34
What is the native VLAN and what problems can a mismatch cause?
The native VLAN is the VLAN whose frames cross a trunk untagged, VLAN 1 by default. Both ends must use the same native VLAN; if they differ, frames leak between VLANs and CDP logs a native VLAN mismatch. For security, set the native VLAN to an unused ID, do not put users in it, and optionally tag it with vlan dot1q tag native to prevent VLAN hopping.
35
Tell me about a time you took initiative beyond your assigned work.
Situation: our team got many Wi-Fi complaints but had no data. Task: nobody had asked, but I wanted to find the cause. Action: I did a walk-through survey with a free tool, mapped channels and signal, and found three APs on the same 2.4 GHz channel and one dead AP. I shared a short report with fixes. Result: after the changes, Wi-Fi tickets dropped by about 60 percent in a month.
36
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.
Few big employers listed in Thiruvananthapuram?
Many Thiruvananthapuram candidates also apply to teams in Bangalore and to remote or hybrid roles. Practise the Bangalore set as well.
Which companies hire CCNA professionals in Thiruvananthapuram?
Companies with large offices in Thiruvananthapuram include many IT services and product firms. Use their company pages below to practise employer-specific sets.
Are CCNA interviews in Thiruvananthapuram different from other cities?
The questions depend more on the company than the city. Thiruvananthapuram's mix of employers decides the style: Data and testing teams here often work with global clients in finance, travel and healthcare
How do I find CCNA jobs in Thiruvananthapuram?
Shortlist companies with Thiruvananthapuram offices, keep your CV focused on CCNA projects, apply on company career pages and job portals with the Thiruvananthapuram filter, and practise the questions on this page before each interview.