HKIE Professional Assessment - Information Discipline flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Nyquist rate

The minimum sampling frequency equal to twice the highest frequency component of a bandlimited signal; sampling below it causes aliasing, which cannot be removed afterwards by filtering.

Shannon capacity formula

C = B·log2(1 + S/N) bits per second, giving the maximum error-free rate over an AWGN channel of bandwidth B with linear signal-to-noise ratio S/N.

Free-space path loss

L(dB) = 32.45 + 20·log10(f in MHz) + 20·log10(d in km). Loss rises with the square of both frequency and distance between isotropic antennas.

MTBF and availability

MTBF is the reciprocal of failure rate λ. Availability equals MTBF divided by MTBF plus MTTR, so shortening repair time raises availability without changing reliability.

Hamming distance rule

With minimum Hamming distance d, a code can detect up to d−1 errors and correct up to the floor of (d−1)/2 errors; larger distance means stronger error control.

CRC versus parity

A cyclic redundancy check detects burst errors using polynomial division and is far stronger than single-bit parity, but neither scheme can correct errors without retransmission.

Horizontal cabling limit

Balanced twisted-pair horizontal channels are limited to 100 m total: 90 m permanent link plus up to 10 m of patch cords at the two ends.

N+1 versus 2N redundancy

N+1 provides one spare unit beyond the load requirement; 2N provides a fully mirrored duplicate system, tolerating loss of an entire side without capacity reduction.

Earned value indices

Cost performance index is EV divided by AC; schedule performance index is EV divided by PV. Values below 1.0 indicate cost overrun or schedule slippage respectively.

Waterfall versus agile choice

Waterfall suits stable, well-defined scope with formal stage gates; agile suits evolving requirements delivered in increments with continuous stakeholder feedback and re-prioritisation.

CIA triad

Confidentiality prevents unauthorised disclosure, integrity prevents unauthorised modification, and availability ensures timely authorised access to systems and data.

Symmetric versus asymmetric encryption

Symmetric ciphers such as AES use one shared key and are fast for bulk data; asymmetric ciphers such as RSA use key pairs for exchange and signatures but are computationally slower.

HMAC purpose

A keyed-hash message authentication code combines a cryptographic hash with a shared secret to verify both data integrity and the authenticity of the message origin.

Hash versus encryption

A hash is a one-way fixed-length digest used for integrity checks; encryption is reversible with the correct key and is used to protect confidentiality of the data.

Digital signature

A hash of the message encrypted with the sender's private key; the receiver verifies it with the public key, proving integrity and origin non-repudiation.

Risk treatment options

Risk equals likelihood times impact. Responses are avoid, reduce, transfer through insurance or contract, or accept; residual risk is recorded and approved by the owner.

Multi-factor authentication

Authentication using factors from at least two distinct categories: something you know, something you have, or something you are; two passwords do not constitute MFA.

3-2-1 backup rule

Keep at least three copies of data on two different media types, with one copy stored off-site; restores must be tested regularly to confirm recoverability.

RPO and RTO

Recovery point objective is the maximum tolerable data loss measured in time; recovery time objective is the maximum tolerable service downtime after an incident.

Data minimisation principle

Only personal data adequate, relevant and necessary for the stated purpose may be collected and retained, and only for as long as that purpose requires.

OSI seven layers

Physical, data link, network, transport, session, presentation and application, from layer one to seven; TCP/IP collapses these into four practical layers.

TCP versus UDP

TCP is connection-oriented with ordered, retransmitted delivery and congestion control; UDP is connectionless without delivery guarantees, suited to real-time and query traffic.

Private IPv4 ranges

10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are non-routable private ranges; 169.254.0.0/16 is link-local and signals DHCP failure.

Usable hosts per subnet

Usable host addresses equal two to the power of host bits, minus two, subtracting the network and broadcast addresses; a /30 therefore yields two usable addresses.

VLAN and 802.1Q

A VLAN creates a separate Layer 2 broadcast domain on shared switching hardware; 802.1Q inserts a 12-bit VLAN identifier into the Ethernet frame tag.

Wi-Fi generation mapping

802.11n is Wi-Fi 4 on 2.4 and 5 GHz; 802.11ac is Wi-Fi 5 on 5 GHz; 802.11ax is Wi-Fi 6 supporting 2.4, 5 and 6 GHz bands.

DHCP DORA sequence

The four-step address assignment exchange: Discover broadcast, Offer from server, Request from client, Acknowledge from server confirming the lease.

DNS record types

A maps a name to IPv4, AAAA to IPv6, CNAME creates an alias, MX names mail servers, TXT holds verification text and PTR supports reverse lookup.

Incident versus problem

An incident is an unplanned service interruption restored by a workaround; a problem is its underlying cause, investigated through root cause analysis.

Change types in IT service management

Normal changes require assessment and change advisory board approval; standard changes are pre-authorised and low risk; emergency changes are implemented urgently and reviewed afterwards.

Project traceability matrix

A requirements traceability matrix links each requirement to design, implementation and test evidence, supporting verification and impact analysis for regulated or safety-critical systems.

Defence in depth

Layering independent controls across physical, network, host, application and data levels so that failure of any single control does not expose the whole system.