Job preparationNetworking
Networking interview questions and answers
The OSI and TCP/IP models, IP addressing, subnetting, DNS, firewalls, NAT and VLANs.
Networking questions are not only for networking roles — developer and support interviews test the fundamentals too.
It nearly always opens with the OSI model. Knowing the seven layers in order gets your confidence up on the first question.
The questions
What is networking and what kinds are there?
What to coverNetworking is the exchange of information between two or more devices. The kinds are LAN (Local Area Network), WAN (Wide Area Network), MAN (Metropolitan Area Network) and PAN (Personal Area Network).
What is the OSI model and what are its layers?
What to coverThe OSI (Open Systems Interconnection) model is a framework describing the layers of networking and what each does. The layers are Physical, Data Link, Network, Transport, Session, Presentation and Application.
What is the TCP/IP model and what are its layers?
What to coverTCP/IP is the communication protocol used on the internet and similar networks. Its layers are Link, Internet, Transport and Application.
What is IP addressing and what kinds are there?
What to coverAn IP address is a numeric label that uniquely identifies every device on a network. The kinds are IPv4 (32-bit) and IPv6 (128-bit).
What is subnetting and why is it used?
What to coverSubnetting divides a larger network into smaller subnets. It improves network management, security and efficiency.
What is DNS and how does it work?
What to coverDNS is the system that turns a domain name into an IP address, so people can reach a website by name instead of by number.
What is a network protocol, and what are the most common ones?
What to coverA network protocol is a set of rules and procedures for exchanging data between devices on a network. Common ones are HTTP, HTTPS, FTP, SMTP, SNMP, TCP and UDP.
What is a firewall and how does it work?
What to coverA firewall is a network security system that controls incoming and outgoing traffic against a set of rules. It prevents unauthorised access to the network.
What is NAT and why is it used?
What to coverNAT (Network Address Translation) converts the private IP addresses on a network into public addresses usable on the internet. It is used to conserve addresses and to add a layer of security.
What is a VLAN and what are its benefits?
What to coverA VLAN is a logical division of a network, used to separate traffic and security across physical networks. The benefits are traffic segmentation, security, and easier management.
Tips for this round
- Give the TCP/UDP difference with an example — a video call is UDP, a file download is TCP. One line and it is clear.
- On DNS, do not stop at the definition; walk through how a lookup is actually resolved.