The CompTIA Network+ is a vendor-neutral exam used to gauge an IT professional’s knowledge about installing, configuring and managing network infrastructure. Obtaining a Network+ certification can open up a path to numerous job types, including:

  • Systems administrator
  • Information technology manager
  • Network administrator
  • Network engineer
  • Information technology specialist
  • Helpdesk technician

Below are some technical questions you may be asked during an interview.

  1. Define a network.

A network is a group of computers, routers, cables and other hardware that connect users, so they can share files, email and connect to the Internet. This is a basic question used to gauge your understanding of networking basics.

  1. What is a node?

Nodes are any desktop, server or virtual machine on the network. A cable or wireless connection connects these devices, but each device on the network is considered a node.

  1. What does a router do?

A router directs traffic from one section of the network to another. Routers are different than hubs because they direct traffic rather than broadcast signals across the entire network.

  1. What protocol can you use to automatically assign IP addresses?

The DHCP protocol automatically assigns IP addresses to desktops, servers or printers. However, your servers and printers should have a static IP address. You can still assign these addresses in the DHCP server settings.

  1. What is a protocol?

A protocol is a set of instructions that guide the communication of networks.  The Internet uses the TCP/IP protocol, which is mostly used in private networks as well. The TCP/IP protocol is what allows devices to communicate with a specific “language,” or set of rules, that allow each device to read and reply to network messages.

  1. If your users are unable to access a server, what things can you do to test server connectivity?

You can use the “ping” command to see if packets are returned. Ping will tell you that the server is turned on and connected. You can also remote into the computer to see if it’s running slow. Use custom tools to check for server resources.

  1. What is the physical layer in the OSI model?

The physical layer is basically the ones and zeros that transport information across the cables of the network.

  1. What is the network layer of the OSI model?

The network layer performs two type of functions: routing and assigning addresses. Routing is the process of assigning traffic to a different segment of the network. Assigning addresses assigns IP addresses to each node on the network, so they can be found and communicate on the network.

  1. What is the process used to protect the company from losing massive data and loss?

Disaster recovery is used to make backups, store data safely and secure data from hackers. DR also makes sure users are able to work even after a disaster.

  1. What is a subnet?

A subnet is a segmented part of the network separated by a router. You use subnets to reduce traffic and congestion on the network and add security through the router.

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  1. In subnetting, mask /24 has how many addresses and hosts? How is the netmask represented?

/24 has 256 addresses and 254 hosts. The netmask is 255.255.255.0.

  1. Name some open-source network analysis/scanning tools that could be used to discover weaknesses?

NMap, Metaspoit and Nessus.

  1. Describe the TCP three-way handshake process.

Syn – Syn/Act – Ack – the client node sends a SYN packet to the server. The server has an open port to accept new connections. When the SYN is received, it sends a confirmation SYN/ACK. Once the client receives the SYN/ACK, it sends it acknowledgement ACK packet back. Once complete, the client and server can communicate freely.

  1. What is seen in a typical CISCO router configuration?

Interface information, static routes, VPN connections, ACLs, IOS, time zones, users and password hashes

  1. Name a protocol analyzer?

Wireshark

  1. Name some routing protocols?

Border gateway protocol (BGP), external gateway protocol (EGP), routing information protocol (RIP), open shortest path first (OSPF) and enhanced Internet gateway routing protocol (EIGRP); Cisco no longer supports the Internet gateway routing protocol, which was a RIP alternative. The EIGRP is its replacement.

  1. What is the difference between TCP and UDP?

TCP is connection-oriented and UDP is connectionless.

  1. Name some mail protocols and their port numbers?

SMTP (25), Pop (110) and IMAP (143).

  1. How do you determine the type of web server used on a certain site?

By performing a banner grab.

  1. What is port 53?

DNS

  1. When you type www.google.com or any URL into the browser bar, what happens in the backend?

The address goes to the DNS server to resolve the domain name to the IP address. (The interviewer may follow up with the following question: Which DNS server? The answer is the one specified in your network config, which then contacts the authoritative name server for the IP address.)

  1. If you ping a site, like www.google.com, and the TTL said 123, what does that tell you?

Windows uses a TTL of 128 by default, so this suggests the target host was five hops away. This is because each hop decreases the TTL by one.

  1. What command would you use to get the local routing table listing?

Netstat –r

  1. How many layers are in the OSI model and what are they?

There are seven layers to the OSI model: physical, data link, network, transport, session, presentation and application.

  1. What are the benefits of subnetting?

It makes network administration and routing more efficient by reducing network traffic and the size of routing tables. Subnetting allows the admin to divide a network into virtually defined segments. Isolating part of the network also adds a layer of security.

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Conclusion

If you are granted an interview based on your Network+ certification, the interviewer will ask a lot of networking-related questions. Make sure you understand subnetting, how to configure firewalls, routers, switches, hubs, iptables, TCP and UDP, and memorize the most popular network protocols and port numbers. Often interviewers will ask about FTP, DNS, Telnet, email protocols, HTTP and/or HTTPS. Know and understand the OSI model, the netstat command, tcpdump, ping and telnet.

Good Luck!