Networking
23 free questions with worked answers, and 635 more in the full bank.
Free questions
What device is commonly used to connect multiple computers within a LAN?
1 mark · Easy
Which cable type is most commonly used for Ethernet connections?
1 mark · Easy
What is the purpose of DNS?
1 mark · Easy
Which of the following tools is used to diagnose network connectivity issues?
1 mark · Easy
What does VPN stand for?
1 mark · Easy
What is the primary function of a router?
4 marks · Hard
What protocol is used to send email?
4 marks · Hard
A user reports that they are unable to access the hospital management system due to a firewall blocking the connection. What should you do to resolve this issue?
4 marks · Hard
A junior admin is looking at a packet capture and notices MAC addresses are being used to forward frames. Which OSI layer is responsible for this activity?
1 mark · Easy
While investigating a slow application, you observe TCP window size zero messages in Wireshark. At what layer of the OSI model does this flow control issue reside?
3 marks · Medium
Users report that their web browsers are failing to negotiate TLS encryption with a newly deployed internal server. Which OSI layer is failing to establish this secure connection?
4 marks · Hard
An engineer connects a spectrum analyzer to a coax cable to check for electromagnetic interference. What OSI layer is being analyzed?
1 mark · Easy
A routing loop has caused TTL values to expire, dropping IP packets. In which OSI layer does the TTL field exist?
3 marks · Medium
During a network outage, a technician finds that a fiber optic cable was accidentally severed. Which layer of the OSI model is directly impacted by this physical break?
1 mark · Easy
An application requires persistent connections and checkpointing during a large file transfer so it can resume if interrupted. Which OSI layer provides these dialog control features?
4 marks · Hard
You are troubleshooting an IPsec VPN tunnel where ESP packets are being dropped by an intermediary firewall. Which OSI layer protocols are being blocked?
3 marks · Medium
A user complains that they cannot access a specific internal webpage, receiving an HTTP 500 error. At what OSI layer is this error generated?
1 mark · Easy
A switch receives a frame with a destination MAC address of FF:FF:FF:FF:FF:FF. Which OSI layer is responsible for flooding this frame out all ports?
3 marks · Medium
A small office connects all their computers to a single central switch. What physical topology is in use?
1 mark · Easy
An enterprise connects its 5 branch offices directly to every other branch office using point-to-point links for maximum redundancy. What topology does this represent?
3 marks · Medium
A legacy industrial control system uses a single coaxial cable that loops through each machine on the factory floor. If a break occurs, the entire segment fails. What topology is described?
4 marks · Hard
A campus network consists of several star-topology building networks connected together via a high-speed fiber backbone ring. Which term best describes this overall design?
1 mark · Easy
To save costs, a regional ISP connects its routers in a circle, where each router only links to its two nearest neighbors. What topology is deployed?
3 marks · Medium
More Networking questions (page 6 of 11)
Answers and explanations are in the full bank.
- The ICT officer of a district is writing the rules for a new firewall in front of the district's servers. Which approach follows good practice? · 2 marks
- A firewall allows staff PCs to open outbound connections to TCP 443 on the internet but has no inbound rule for web traffic. Pages still load. Why do the replies get through? · 3 marks
- Forty computers in a school share a single public IP address to reach the internet. How does the router know which computer each returning packet belongs to? · 3 marks
- A cooperative in Musanze hosts its booking website on a server inside its office network, behind a router doing NAT. What must be configured so that customers on the internet can reach it? · 2 marks
- In classic active-mode FTP, which ports carry the control commands and the file data? · 2 marks
- Users can log in to an FTP server behind the firewall, but directory listings and file transfers hang. The firewall allows only TCP 21. What is the likely cause? · 3 marks
- A supplier offers to deliver reports by FTPS or by SFTP. The ministry's firewall already allows SSH to the file server and nothing else. Which option works without a new firewall rule? · 2 marks
- A network technician backs up the configuration of every switch to a server using a very simple file-transfer protocol that has no login at all. Which protocol and port are these switches using? · 2 marks
- A developer at a software company in Kigali runs a test web server that is reached at http://server:8080. What is port 8080 commonly used for? · 1 mark
- A firewall at a university allows TCP 443 but blocks UDP 443. Websites still load, but browser tools show they are using HTTP/2 instead of HTTP/3. Why? · 3 marks
- A security scan of a government web server reports that it still accepts SSL 3.0 and TLS 1.0. What should be done? · 2 marks
- Since this morning, every browser in a district office shows a security warning when staff open the internal HR portal. The certificate details show a validity date that ended yesterday. What is the right fix? · 2 marks
- A web server becomes unreachable. Its connection table is full of thousands of half-open connections from many addresses that sent SYN but never completed the handshake. What is happening? · 3 marks
- Which DNS record type maps a host name directly to an IPv4 address? · 1 mark
- A university gives its web server an IPv6 address so that IPv6-only phones can reach it. Which record must be added to the university's DNS zone? · 2 marks
- A new agency has registered its domain and set up a mail server, but mail sent to its addresses from outside never arrives, while its website works. Which DNS record is most likely missing? · 2 marks
- An organisation wants both www.agency.example and portal.agency.example to lead to the same server, so that only one record needs changing if the server's address changes. Which record type makes one name an alias of another? · 2 marks
- Some external mail servers reject messages from a ministry's mail server because a lookup of its IP address returns no name. Which record, usually set up with the internet provider, is missing? · 2 marks
- Criminals send fake invoices that appear to come from a company's own domain. Which DNS entry lets receiving mail servers check whether a sending server is authorised to send mail for that domain? · 3 marks
- How does DKIM help a receiving server trust that an email really came from the domain it claims and was not altered on the way? · 3 marks
- The ICT team moves a website to a new server and updates its A record. Hours later, some users still reach the old server while others reach the new one. What explains this? · 2 marks
- Which command-line tool, available on both Windows and Linux, queries DNS to show the IP address a name resolves to? · 1 mark
- A secondary DNS server at a branch office stopped receiving updates from the primary after a new firewall was installed between them. Ordinary name lookups through the firewall still work. The firewall allows only UDP 53. What is blocked? · 3 marks
- Which technology protects users from forged DNS answers, such as a poisoned cache that sends them to a fake banking site, by letting resolvers verify that records came from the real zone? · 3 marks
- A citizen following an old link to a district's website gets an HTTP 404 error. What does it mean? · 1 mark
- After permissions on a web folder are changed, users receive HTTP 403 when opening reports that were visible yesterday. What does 403 indicate? · 2 marks
- Right after a new version of a payroll web application is deployed, every page returns HTTP 500. Where should the ICT officer look first? · 2 marks
- An organisation wants visitors and search engines that request http://agency.example to be sent permanently to https://agency.example. Which HTTP response should the server return? · 2 marks
- When a citizen submits a filled-in application form on a website, which HTTP method normally sends the form data to the server in the body of the request? · 1 mark
- Even though a bank's site redirects HTTP to HTTPS, an attacker on public Wi-Fi could intercept the very first plain-HTTP request. Which response header tells browsers to use only HTTPS for the site in future? · 3 marks
- Besides encryption, what does the TLS certificate of a site such as a ministry's e-services portal give the visitor? · 2 marks
- HTTP treats every request as independent. How does a web application keep a user logged in as they move from page to page? · 2 marks
- A company's mail server suddenly appears on spam blacklists. Logs show it accepting and forwarding mail from unknown internet hosts to outside addresses. What is the misconfiguration? · 3 marks
- A domain has two MX records: mail1 with preference 10 and mail2 with preference 20. How do sending servers use them? · 2 marks
- Applications query Active Directory for user accounts and groups with a directory protocol. Which protocol and default port is it? · 1 mark
- A web application logs users in by sending their domain username and password to Active Directory over plain LDAP. How should this be secured? · 2 marks
- A firewall between a branch office and the domain controllers blocks domain logons, although DNS and LDAP are allowed. Which port used for Kerberos authentication should be opened? · 2 marks
- A school filters harmful websites by controlling DNS on port 53, yet some browsers still reach blocked sites without any VPN. Which feature is most likely letting them bypass the filter? · 3 marks
- A university wants each staff member to join the office Wi-Fi with their own domain username and password, instead of one shared password. Which combination provides this? · 3 marks
- A telecom operator wants every engineer's login to its routers checked centrally, with per-command authorisation and the whole session payload encrypted. Which AAA protocol suits device administration best? · 3 marks
- A site-to-site IPsec VPN between a head office in Kigali and a branch in Rusizi will not come up after a new firewall is installed at the branch. What must the firewall allow? · 3 marks
- Staff travelling to conferences find that the office's IPsec VPN fails on many hotel networks, but an SSL VPN works almost everywhere. Why? · 2 marks
- An old router offers PPTP for staff remote access on TCP 1723. Why should it not be used? · 2 marks
- New IP phones at a district hospital must register with the hospital's IP-PBX. Which protocol and default port handle call set-up and registration? · 2 marks
- After a firewall change, calls between two offices connect and the phones ring, but neither side can hear the other. What is most likely being blocked? · 3 marks
- A technician supports a Linux desktop using a VNC viewer. On which port does the VNC server listen for the first display? · 1 mark
- A web application server at a university cannot connect to its MySQL database on another server, though both can ping each other. Which port should the firewall between them allow? · 2 marks
- Which protocol provides the encryption in HTTPS? · 1 mark
- A health programme installs battery-powered temperature sensors in vaccine fridges at rural health centres, sending readings over weak mobile connections. Which protocol is designed for this kind of lightweight publish/subscribe messaging? · 3 marks
- A firewall rule between the staff VLAN and the printer VLAN at a sector office must allow direct printing to network printers. Which port do most network printers accept raw print jobs on? · 2 marks
- Before a PC can send a packet to its default gateway on the same Ethernet network, it must learn the gateway's MAC address. Which protocol does it use? · 1 mark
- On an IPv6-only network there is no ARP. How do IPv6 hosts discover the MAC addresses of their neighbours and routers? · 3 marks
- How does traceroute (tracert on Windows) discover each router on the path to a destination? · 3 marks
- In which order are the four messages exchanged when a client obtains an address from a DHCP server? · 2 marks
- The shared printer at a sector office gets a different IP address every few weeks, and staff PCs then lose it. The office wants to keep using DHCP. What is the best fix? · 2 marks
- Several PCs in a TVET school suddenly get addresses in 192.168.0.x with an unknown gateway, instead of the school's 10.20.0.x range. A student has plugged a home router into a wall socket. Which switch feature prevents this? · 3 marks
- Logs on a public-facing Linux server show thousands of SSH password guesses every day. Which change most improves the security of SSH logins? · 2 marks
- Linux servers in a data centre share folders with each other using NFS. Which port does NFS use by default? · 1 mark
- An audit of an old Windows file server finds it still answering on UDP 137, UDP 138 and TCP 139. Which legacy service is this? · 2 marks
- Internet providers connected at the Rwanda Internet Exchange (RINEX) exchange routes with one another so that local traffic stays in the country. Which protocol, running on TCP port 179, do they use? · 3 marks