36 practice questions with answers for CCNA interviews in Lucknow.
CCNA jobs in Lucknow
Lucknow's tech job market is smaller but growing, led by IT-services delivery centres, government-tech projects and start-ups. Many Lucknow candidates target Noida and Gurgaon roles or remote jobs, so interviews follow the NCR pattern.
Below are 36 questions that match the mix of service, product and domain employers hiring network support engineers in Lucknow.
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01
How do you configure port security with sticky MACs?
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
03
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.
04
How do you verify VLANs, trunks and MAC learning on a switch?
These show commands cover most VLAN troubleshooting.
show vlan brief
show interfaces trunk
show interfaces Gi1/0/5 switchport
show mac address-table vlan 20
show mac address-table address 0050.56ab.cdef
show interfaces status
They show VLAN membership, allowed and active VLANs on trunks, native VLAN and where each MAC was learned.
05
A new VLAN's users do not get DHCP addresses, but other VLANs work. What do you check?
I check that the SVI for the new VLAN is up and has ip helper-address pointing to the DHCP server, that the server has a scope for that subnet with the right gateway, and that the scope is activated. I confirm the VLAN is allowed on trunks. If DHCP snooping is enabled, I check the uplink is trusted, otherwise offers from the server are dropped.
06
What are the default administrative distances you should know?
Connected 0, static 1, EIGRP summary 5, eBGP 20, internal EIGRP 90, OSPF 110, IS-IS 115, RIP 120, external EIGRP 170 and iBGP 200. A value of 255 means the route is never used. AD compares trust between sources, so a static route with AD 1 beats OSPF for the same prefix unless you configure a floating static with a higher AD.
07
Your company is running out of IP addresses on a /24 user subnet. What options do you have?
Options: expand to a /23 if the adjacent block is free and update the router and DHCP scope; create a new VLAN and subnet for some users, which also limits broadcast size; shorten DHCP lease times if many guest devices hold leases; and move printers, phones and IoT devices to their own subnets. Long term, plan an addressing scheme with growth headroom and consider dual-stack IPv6.
08
What are the first hop redundancy protocols and how does HSRP work?
FHRPs give hosts a virtual gateway IP shared by two or more routers. HSRP is proprietary: routers elect an active router by highest priority (default 100), and the standby takes over the virtual IP and MAC if hellos stop. Preempt lets a higher priority router reclaim the role. VRRP is the open standard, and GLBP adds load sharing across several routers.
09
Tell me about a time you worked with a difficult end user during a ticket.
Situation: a senior manager was angry that his laptop lost network access before a client call. Task: fix it fast and calm him down. Action: I listened, gave a clear time estimate, found the port had been moved to a wrong VLAN in a recent change, corrected it and confirmed the call worked. Result: he was back online in ten minutes, and I added a port description check to our change process.
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.
11
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.
12
Two hosts are in the same VLAN but one has mask /24 and the other /25. What problems may occur?
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.
13
After adding a new VLAN, users on one access switch cannot use it but others can. Why?
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.
14
What is a wildcard mask and how is it used in ACLs?
A wildcard mask tells the router which bits must match: 0 means must match and 1 means ignore. It is often the inverse of the subnet mask, so 192.168.1.0 0.0.0.255 matches the whole /24. host 10.1.1.1 equals 0.0.0.0 and any equals 255.255.255.255. Wildcards are also used in OSPF network statements. Calculate it by subtracting the mask from 255.255.255.255.
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.
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
Redundant Layer 2 links create loops, and Ethernet frames have no TTL, so broadcasts circulate forever, causing broadcast storms, MAC table instability and duplicate frames. STP (802.1D) blocks redundant paths so there is one loop-free path to every switch, and unblocks a backup link if the active one fails. Without it, a single loop can take down a whole campus within seconds.
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.
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.
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.
22
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.
VLAN Trunking Protocol shares VLAN definitions from a server switch to clients in the same VTP domain. Modes are server, client, transparent and off. The risk is that a switch with a higher configuration revision number can overwrite and wipe VLANs across the domain. Many networks use transparent mode or VTP version 3 with a primary server to avoid this.
24
Logs show MAC address flapping for several hosts between an access port and an uplink. What do you check?
MAC flapping means the switch sees the same source MAC arriving on two ports, which usually points to a Layer 2 loop, a misconfigured server NIC team, or a virtual machine host bridging two uplinks. Check show mac address-table for the MAC, trace both ports, verify STP state and look for unmanaged switches or hypervisor teaming in active-active mode without a matching port channel. Fix the loop or teaming, and keep BPDU Guard on access ports.
25
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.
When a host needs the MAC for an IP on its subnet, it broadcasts an ARP request and the owner replies with a unicast ARP reply; the result is cached. For remote destinations the host ARPs for its default gateway. A gratuitous ARP is an unsolicited announcement of a host's own IP-to-MAC mapping, used after failover, for example by HSRP, to update switch and host tables.
27
What are the basic steps to configure a WLAN with WPA2 or WPA3 on a controller GUI?
Steps on a typical WLC GUI: create a dynamic interface with VLAN, IP and DHCP server; go to WLANs and create a new WLAN with profile name and SSID; map it to the dynamic interface; under Security choose WPA2 or WPA3 with PSK or 802.1X and add the RADIUS server for enterprise; set QoS profile; enable the WLAN and apply it to AP groups.
28
How do you configure IPv4 static and default routes?
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
29
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.
30
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.
31
Users suddenly receive IP addresses from a wrong subnet. What do you suspect and how do you fix it?
A rogue DHCP server, often a home router plugged into a wall port, is answering requests. I find it by checking the DHCP server IP on an affected client with ipconfig /all, then tracing its MAC with show mac address-table. I shut that port, and prevent it permanently by enabling DHCP snooping on user VLANs with only uplinks trusted.
32
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.
A floating static route is a backup static route with a higher administrative distance than the primary route, so it stays out of the routing table until the primary disappears. For example, if OSPF (AD 110) learns the main path, ip route 0.0.0.0 0.0.0.0 203.0.113.1 200 installs only when OSPF loses the route. It is common for backup internet or 4G links.
34
Tell me about a time you found a security issue and reported it.
Situation: during a routine audit I noticed SNMP v2c with the default community public on several access switches. Task: close the gap without disrupting monitoring. Action: I reported it to my lead with evidence, proposed SNMPv3 with an ACL, tested with the monitoring team and rolled out in two batches. Result: the risk was closed in a week and SNMP checks were added to our device baseline.
Rapid PVST+ runs 802.1w per VLAN. It uses a proposal and agreement handshake on point-to-point links so ports move to forwarding in under a second, instead of waiting on timers. It has port roles root, designated, alternate and backup, and states discarding, learning and forwarding. Alternate ports provide an instant backup root port. It is the default on most modern IOS switches.
36
Auditors find that network devices use shared admin passwords and Telnet. What is your remediation plan?
Disable Telnet with transport input ssh, enable SSH v2, and move admin login to AAA with TACACS+ so each engineer has a personal account with command authorisation and accounting logs. Keep one local fallback account in a password vault. Restrict VTY access with an ACL to the management subnet. Roll out with automation, test on a pilot, then document it for the audit.
Which companies hire CCNA professionals in Lucknow?
Companies with large offices in Lucknow include HCLTech. Use their company pages below to practise employer-specific sets.
Are CCNA interviews in Lucknow different from other cities?
The questions depend more on the company than the city. Lucknow's mix of employers decides the style: Many Lucknow candidates target Noida and Gurgaon roles or remote jobs, so interviews follow the NCR pattern
How do I find CCNA jobs in Lucknow?
Shortlist companies with Lucknow offices, keep your CV focused on CCNA projects, apply on company career pages and job portals with the Lucknow filter, and practise the questions on this page before each interview.