Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About Dell Technologies hiring for CCNA roles
Dell Technologies makes PCs, servers, storage and networking products and provides related services. Its India centres in Bengaluru and Hyderabad work on software engineering, testing, data, IT and support functions. It hires for software engineers, test engineers, data analysts and data engineers. Several teams support global product lines and customers.
For CCNA roles, this Dell Technologies practice set focuses most on Switching and VLANs (7), IP Services (7), IP Addressing and Subnetting (4), Network Security (4). It has 2 easy, 19 medium, 9 hard questions, so you can start easy and work up to the harder ones.
Company type
Hardware & semiconductors
Headquarters
Round Rock, Texas, USA
Main India offices
Bengaluru, Hyderabad
Dell Technologies CCNA interview process
Online assessment (aptitude + technical)
Technical round 1
Technical round 2
Managerial round
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
Solved for Dell TechnologiesStart practicing
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Routers send hellos to 224.0.0.5. They become neighbours if area ID, subnet and mask, hello and dead timers, authentication and stub flags match, and the router IDs are unique. States go Down, Init, 2-Way, ExStart, Exchange, Loading and Full. In ExStart and Exchange they agree master and slave and swap database descriptions, which is where an MTU mismatch causes a stuck adjacency.
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.
04
An internal web server must be reachable from the internet on a public IP. How do you set it up?
Use static NAT or port forwarding so the public IP maps to the server's private IP, for example ip nat inside source static tcp 192.168.1.20 443 203.0.113.10 443. Add an ACL or firewall rule allowing only port 443 inbound, put the server in a DMZ VLAN, and create a public DNS record. Ideally place a firewall or reverse proxy in front instead of exposing the server directly.
Cost equals reference bandwidth divided by interface bandwidth. The default reference is 100 Mbps, so FastEthernet, Gigabit and 10 Gigabit all get cost 1, which hides the faster links. Change it with auto-cost reference-bandwidth 100000 on every router so 1G becomes 100 and 10G becomes 10. You can also set ip ospf cost directly on an interface. Path cost is the sum of outgoing interface costs.
06
After moving DHCP to a new central server, remote PCs get addresses but IP phones fail to download their configuration. What do you check?
The phones need extra DHCP options that were probably not copied, such as option 150 or option 66 for the TFTP or call server and sometimes a voice VLAN option. Check the scope options on the new server, confirm the relay on each SVI points to it, and capture the DHCP offer to see which options arrive. Also verify the voice VLAN scope exists and that ACLs allow TFTP from the phone subnets to the call server.
07
How do you configure NTP, syslog and SNMPv3 on a device?
Choppy voice under load means congestion on the WAN. I make sure phones mark RTP as EF and the access switches trust phone markings, then on the WAN router create a policy with a low latency priority queue for EF limited to the needed bandwidth, CBWFQ for other classes, and shaping to the real carrier rate so queuing happens on my router, not the provider's.
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
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.
11
After a core switch replacement, ping works across the campus but large file transfers and some VPN sessions hang. What do you suspect?
Suspect an MTU mismatch. Small pings fit in one frame, but full-size packets are dropped when one link or the new switch uses a smaller MTU, or when ICMP is blocked so Path MTU Discovery fails. Test with ping using a size of 1472 and the do-not-fragment bit, compare interface MTU on both ends, and check jumbo frame settings. Fix by matching MTU end to end or adjusting TCP MSS on tunnel interfaces.
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.
DAI checks ARP packets on untrusted ports against the DHCP snooping binding table and drops ARP replies whose IP-to-MAC mapping does not match. This stops ARP spoofing and man-in-the-middle attacks where an attacker claims to be the default gateway. Static hosts need ARP ACLs. It requires DHCP snooping enabled in the same VLAN and trusted uplink ports.
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
15
A security scan shows that switch and router management interfaces are reachable from user VLANs. How do you lock down management access?
Move management to a dedicated VLAN or out-of-band network, ideally in a management VRF. Apply an access-class ACL on VTY lines allowing only the jump host subnet, disable Telnet and HTTP, keep SSH version 2 and HTTPS only if needed, and use AAA with TACACS+ for per-user login and logging. Add control plane policing, block management subnets at the user VLAN gateways and rescan to confirm the fix.
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.
17
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.
18
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.
19
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.
20
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.
21
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.
22
Guest Wi-Fi users must reach only the internet, not internal networks. How do you enforce it?
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.
23
An SVI shows status down/down even though it is configured. What could be wrong?
An SVI comes up only if the VLAN exists in the VLAN database and at least one access or trunk port in that VLAN is up and forwarding, and the SVI is not shut down. So I check show vlan brief for the VLAN, check that at least one port in it is connected, check trunks allow it, and run no shutdown on the SVI. On Layer 3 switches, ip routing must be enabled for routing.
24
A trunk between two switches is not forming. What would you check?
I check show interfaces trunk and show interfaces switchport on both sides. Common causes are mismatched modes (both dynamic auto), one side hard-coded as access, encapsulation not set on older switches, or the port being err-disabled. Native VLAN mismatch and allowed list differences do not stop the trunk but break traffic. Best fix is switchport mode trunk on both ends with nonegotiate.
25
You have 192.168.10.0/24 and need subnets for 100, 50, 20 hosts and two point-to-point links. Design it with VLSM.
Netmiko handles SSH sessions; keep credentials in a file or vault, not the script.
import yaml
from netmiko import ConnectHandler
# r1.yml holds device_type, host, username, password
with open('r1.yml') as f:
device = yaml.safe_load(f)
with ConnectHandler(**device) as conn:
output = conn.send_command('show ip interface brief')
print(output)
27
A new lightweight AP does not join the controller. How do you troubleshoot?
I check the AP gets a DHCP address and can reach the WLC management IP. It discovers the controller through DHCP option 43, the standard CAPWAP controller DNS name, broadcast or a primed controller IP, so I verify one of these. Then I check UDP 5246 and 5247 are not blocked, the AP's clock and certificate are valid, the country code matches, and the WLC has AP licences available.
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.
29
What is a collision domain and a broadcast domain?
A collision domain is a segment where two devices sending at the same time can collide; every switch port is its own collision domain, and with full duplex collisions do not occur. A broadcast domain is the set of devices that receive a Layer 2 broadcast. Routers and VLANs separate broadcast domains, so one VLAN equals one broadcast domain.
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
Tips to crack the Dell Technologies CCNA interview
Revise storage and server basics, such as RAID, virtualisation and backup, if applying for infrastructure teams.
Practise testing concepts and Python automation, which are common requirements for Dell QA roles.
Read about Dell's AI servers and infrastructure business, which has become a major growth area.
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; Dell Technologies interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the Dell Technologies CCNA interview?
Candidates usually go through 5 stages: Online assessment (aptitude + technical); Technical round 1; Technical round 2; 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 Dell Technologies CCNA interview?
This practice set leans on Switching and VLANs (7), IP Services (7), IP Addressing and Subnetting (4), Network Security (4). Revise those first, then practise explaining one or two of your own projects end to end, because most Dell Technologies interviewers ask you to walk through real work.
Are these the exact questions asked at Dell Technologies?
No. These are curated practice questions that match the skills and difficulty usually tested in hardware & semiconductors interviews like Dell Technologies's. They are not a leaked or verified list of past questions.
Where does Dell Technologies hire CCNA professionals in India?
Dell Technologies has large teams in Bengaluru, Hyderabad. Openings and locations change often, so check the Dell Technologies careers page and filter by city and experience.