CompTIA A+ / Network+ / Security+ CompTIA Network+: Networking Concepts & Models (N10-009) Flashcards

24 sample cards from the CompTIA Network+: Networking Concepts & Models (N10-009) deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the full (uncompressed) length of an IPv6 address and how is it written?

   128 bits, written as eight groups of four hexadecimal digits separated by colons, e.g., 2001:0db8:0000:0000:0000:0000:0000:0001.

2. State the two IPv6 zero-compression rules.

   1) Leading zeros in any group may be omitted (0db8 becomes db8). 2) One contiguous run of all-zero groups may be replaced with a double colon '::', and only once per address.

3. What is the IPv6 prefix for link-local addresses and global unicast addresses?

   Link-local addresses use fe80::/10 (auto-configured on every interface). Global unicast addresses currently use 2000::/3.

4. What is EUI-64 and how does it build the interface ID from a MAC address?

   EUI-64 derives a 64-bit interface ID from a 48-bit MAC by splitting it, inserting FFFE in the middle, and flipping the 7th bit (U/L bit) of the first octet. Example: MAC becomes a 64-bit host portion for SLAAC.

5. What is SLAAC in IPv6?

   Stateless Address Autoconfiguration: a host generates its own IPv6 address using the network prefix learned from a Router Advertisement (RA) combined with a self-generated interface ID, without a DHCP server.

6. What is the difference between NAT, PAT, and static NAT?

   Static NAT maps one private address to one public address (one-to-one). Dynamic NAT maps private addresses to a pool of public addresses. PAT (NAT overload) maps many private addresses to one public address using unique source port numbers.

7. Why is PAT (Port Address Translation) the most common form of NAT for home/small networks?

   Because it lets many internal hosts share a single public IPv4 address by tracking unique source-port-to-host mappings, conserving scarce public IPv4 addresses.

8. In NAT terminology, define 'inside local' and 'inside global'.

   Inside local is the private (RFC 1918) address of an internal host as seen on the inside network. Inside global is the public address that represents that host externally after translation.

9. What is the function of DNS and what default port does it use?

   DNS (Domain Name System) resolves human-readable hostnames to IP addresses (and vice versa). It uses port 53, with UDP for most queries and TCP for zone transfers and large responses.

10. Match these DNS record types to their purpose: A, AAAA, CNAME, MX, PTR, TXT.

    A = hostname to IPv4. AAAA = hostname to IPv6. CNAME = alias to another name. MX = mail exchanger for a domain. PTR = reverse lookup (IP to name). TXT = arbitrary text (SPF/DKIM/verification).

11. What are the four messages in the DHCP DORA process?

    Discover (client broadcast), Offer (server proposes a lease), Request (client requests the offered address), Acknowledge (server confirms the lease). Mnemonic: DORA.

12. What is the purpose of NTP and which port does it use?

    NTP (Network Time Protocol) synchronizes clocks across devices using a hierarchy of stratum levels. It uses UDP port 123. Accurate time is essential for logging, certificates, and authentication.

13. List the well-known ports for FTP, SSH, Telnet, SMTP, HTTP, and HTTPS.

    FTP = 20/21 (TCP), SSH = 22 (TCP), Telnet = 23 (TCP), SMTP = 25 (TCP), HTTP = 80 (TCP), HTTPS = 443 (TCP).

14. List the ports for DNS, DHCP, TFTP, SNMP, and RDP.

    DNS = 53 (UDP/TCP), DHCP = 67/68 (UDP), TFTP = 69 (UDP), SNMP = 161/162 (UDP), RDP = 3389 (TCP).

15. What ports do POP3, IMAP, and their secure (TLS) versions use?

    POP3 = 110, POP3S = 995. IMAP = 143, IMAPS = 993. All are TCP.

16. What ports do LDAP, LDAPS, and SMB use?

    LDAP = 389 (TCP/UDP), LDAPS = 636 (TCP), SMB = 445 (TCP).

17. What is the difference between SDN and traditional networking in terms of control and data planes?

    Traditional devices have the control plane (decision-making) and data plane (forwarding) on each device. SDN (Software-Defined Networking) centralizes the control plane in a controller that programs the forwarding/data plane of devices via APIs (e.g., OpenFlow / southbound interface).

18. Define the three cloud service models: IaaS, PaaS, and SaaS.

    IaaS provides virtualized infrastructure (VMs, storage, networking) — you manage OS and up. PaaS provides a development/runtime platform — you manage only your app and data. SaaS delivers ready-to-use applications over the web — the provider manages everything.

19. Compare public, private, hybrid, and community cloud deployment models.

    Public: shared multi-tenant infrastructure owned by a provider. Private: dedicated to a single organization. Hybrid: a mix of public and private connected together. Community: shared by several organizations with common concerns (e.g., compliance).

20. What is multitenancy in cloud computing?

    A single instance of software/infrastructure serves multiple customers (tenants), with logical isolation keeping each tenant's data and configuration separate while sharing the underlying physical resources.

21. What is a VPC and what is a cloud gateway/transit gateway?

    A VPC (Virtual Private Cloud) is a logically isolated virtual network within a public cloud. A transit/cloud gateway interconnects multiple VPCs and on-premises networks, acting as a central routing hub.

22. What is Direct Connect / ExpressRoute and how does it differ from a site-to-site VPN to the cloud?

    Direct Connect (AWS) / ExpressRoute (Azure) is a dedicated private physical connection between on-prem and the cloud, offering consistent low latency and bandwidth. A site-to-site VPN is an encrypted tunnel over the public internet, cheaper but with variable performance.

23. What is Network Function Virtualization (NFV)?

    NFV replaces dedicated hardware appliances (routers, firewalls, load balancers) with software functions (VNFs) running on standard servers/VMs, enabling flexible, scalable, and rapidly deployable network services.

24. What is a VXLAN and what problem does it solve versus traditional VLANs?

    VXLAN (Virtual Extensible LAN) encapsulates Layer 2 frames in UDP (port 4789) to tunnel them over a Layer 3 network. It provides up to about $2^{24}$ (16 million) segments via a 24-bit VNI, far beyond the 4094-VLAN limit of the 12-bit 802.1Q tag, enabling large multitenant overlays.

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CompTIA Network+: Networking Concepts & Models (N10-009) flashcards FAQ