NodnPrivate, APIPA, loopback
- 10 / 172.16–31 / 192.168 private
- 169.254 no DHCP
- 127.0.0.1 and ::1 this host
Study guide · Flashcards & memory notes
Networking & Cloud Flashcards & Memory Notes
40 recall cards for the facts everyday networking and cloud work depends on: ports, private ranges, Wi-Fi bands, DNS and DHCP, and who manages what in each cloud model.
How to use these cards: Say the answer out loud before you flip the card, and mark it honestly. Revisit the cards you missed tomorrow rather than rereading them right away. Progress is kept only while this page is open. For the full explanations behind each card, see the core notes.
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Deck 1 · Addresses, ports, and transport
Private ranges, masks, and the ports that show up in a firewall rule.
1.1Which TCP port does SSH use, and is it encrypted?
TCP 22. SSH encrypts the session. Telnet on TCP 23 does not.
1.2Which ports do HTTP and HTTPS use?
HTTP uses TCP 80 and is not encrypted. HTTPS uses TCP 443 and is protected by TLS.
1.3What are the three private IPv4 ranges?
10.0.0.0/8, 172.16.0.0/12 (172.16 through 172.31), and 192.168.0.0/16.
1.4What does an address in 169.254.0.0/16 mean?
APIPA. The host did not receive a DHCP lease.
Memory note: This is not an RFC 1918 private range.
1.5What is the IPv4 loopback address, and the IPv6 loopback?
127.0.0.1 for IPv4 and ::1 for IPv6. Both mean the host itself.
1.6How many usable hosts are on a /24 network?
254. The mask is 255.255.255.0. Subtract the network and broadcast addresses from 256.
1.7Which ports do DNS and DHCP use?
DNS uses port 53, UDP for lookups and TCP for large replies. DHCP uses UDP 67 on the server and UDP 68 on the client.
1.8What is the difference between TCP and UDP?
TCP is connection-oriented and retransmits lost data. UDP is connectionless and does not guarantee delivery.
1.9Which port is SMTP, and which ports are IMAP and POP3?
SMTP is TCP 25 and sends mail. IMAP is TCP 143 and leaves mail on the server. POP3 is TCP 110 and usually downloads it.
1.10What does an IP address identify, and what does a port identify?
An IP address identifies a host. A port identifies a program on that host.
Deck 2 · Devices, media, and wireless
Which box forwards what, and which band a standard uses.
2.1What is the difference between a switch and a router?
A switch forwards frames using MAC addresses on one local network. A router forwards packets between IP networks.
2.2What does an access point do?
It connects wireless clients to the wired LAN. By itself it does not route between IP networks.
2.3Which 802.11 standard is Wi-Fi 5, and which band does it use?
802.11ac. It uses 5 GHz.
2.4Which 802.11 standard is Wi-Fi 6, and what is Wi-Fi 6E?
802.11ax is Wi-Fi 6. Wi-Fi 6E adds the 6 GHz band and requires WPA3 there.
2.5Which 2.4 GHz channels do not overlap in North America?
Channels 1, 6, and 11.
2.6What is an SSID?
The name of a wireless network. Hiding it does not encrypt the traffic.
2.7Why choose fiber instead of copper for a long or noisy run?
Fiber uses light, so it resists electromagnetic interference and reaches farther than twisted-pair copper.
2.8What is PoE?
Power over Ethernet. The cable carries electrical power as well as data, often for access points and phones.
2.9Which OSI layer uses MAC addresses, and which uses IP addresses?
MAC addresses are layer 2, Data Link. IP addresses are layer 3, Network.
2.10What is the maximum data rate associated with 802.11b, and which band is it?
11 Mbps on 2.4 GHz. 802.11g is 54 Mbps on the same band.
Deck 3 · DNS, DHCP, and troubleshooting
Records, the lease exchange, and the first test to run.
3.1What does an A record store, and what does an AAAA record store?
An A record maps a name to an IPv4 address. An AAAA record maps a name to an IPv6 address.
3.2What is a CNAME record?
An alias from one hostname to another hostname. It does not store an IP address directly.
3.3What is an MX record?
The mail servers that accept email for a domain. It is not the address of a website.
3.4What does DORA stand for in DHCP?
Discover, Offer, Request, Acknowledge.
3.5What is a default gateway?
The router on the host's subnet that forwards traffic to other networks.
3.6A name fails but the public IP answers ping. Where do you look?
DNS. The path works; the name is not resolving.
3.7What does ping prove, and what does it not prove?
Ping shows that a host answers ICMP echo. It does not prove that a TCP port such as 443 is open.
3.8What does tracert or traceroute show?
The routers along the path to a destination. A timeout at one hop can be a filter rather than a dead link.
3.9Which Windows commands release and renew a DHCP lease?
ipconfig /release and ipconfig /renew. ipconfig /flushdns clears the local DNS cache only.
3.10The gateway answers, but a public IP address does not. Where is the problem most likely?
Past the local subnet: routing, NAT, or the provider link. It is not a failed DHCP lease.
Deck 4 · Cloud models and responsibility
Service models, places, storage, and who still has the keys.
4.1In IaaS, who patches the guest operating system?
The customer. The provider operates hardware, networking, storage, and virtualization.
4.2What does the customer manage in SaaS?
Settings, user accounts, and data. The provider operates the application stack.
4.3What is the difference between a public cloud and a private cloud?
Public cloud is multitenant infrastructure owned by a provider. Private cloud is dedicated to one organization.
4.4What is elasticity?
Capacity that grows and shrinks with demand, often automatically. Scalability is the ability to handle more load.
4.5What is the difference between a region and an availability zone?
A region is a geographic area. An availability zone is an isolated site inside that region.
4.6What is the difference between block storage and object storage?
Block storage is a volume attached like a disk. Object storage holds blobs fetched by an API.
4.7What is the difference between a Type 1 and a Type 2 hypervisor?
Type 1 runs on the hardware. Type 2 runs as an application on a host operating system.
4.8How is a container different from a virtual machine?
A container shares the host kernel. A virtual machine runs its own guest operating system.
4.9What is the difference between WPA2 and an open wireless network?
WPA2 encrypts the Wi-Fi traffic. An open network does not. WEP is obsolete, and 6 GHz Wi-Fi 6E requires WPA3.
4.10What does least privilege mean for a cloud service?
Grant only the access that service needs. Prefer a role it can assume over a long-lived access key on disk.
Memory notes
Groupings that make the highest-yield facts easier to recall.
Ports in one line
22 SSH, 53 DNS, 67/68 DHCP, 80 HTTP, 443 HTTPS, 25 SMTP, 143 IMAP, 110 POP3, 445 SMB, 3389 RDP.
Wi-Fi bands
- b/g 2.4 GHz · a/ac 5 GHz
- n and ax both bands · 6E adds 6 GHz
- 2.4 GHz plan: 1, 6, 11
DORA and records
- Discover, Offer, Request, Ack
- A IPv4 · AAAA IPv6 · MX mail · CNAME alias
Cloud boundary
- IaaS you patch the OS
- PaaS you ship the app
- SaaS you manage users and data
First split
169.254 means DHCP. Gateway silent means the local link. Name fails and IP works means DNS. Ping does not prove a TCP port is open.
Continue the networking and cloud study path
Test what you have learned with a timed practice exam.
Overview
Scope, domains, address and port map, cloud models, and a study plan.
Core Notes
Reference notes for layers, addresses, ports, devices, Wi-Fi, DNS, DHCP, and cloud models.
Flashcards & Memory Notes
40 recall cards in four decks, plus memory notes for ports, ranges, and service models.
Practice Exams
200 original questions with custom exams, explanations, and a score report by domain.
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