Every term below is one the lab actually teaches and explains, harvested from the lessons, the exam bank, the game round banks and the practice paths across all sixteen weeks. Nothing here is imported from an outside dictionary: if the lab does not use a word or does not explain it, it is not in this list. Each entry names the week it comes from and links back to the page that teaches it.
An HTTP response telling the browser a move is permanent, which lets a browser or search engine remember the new address and go straight there on future visits.
An HTTP response telling the browser a move is only temporary, so the old URL keeps being treated as correct and checked again on the next visit rather than skipped.
The standard tag a switch adds to a frame crossing a trunk, naming which VLAN the frame belongs to, removed again at the far end.
A DNS entry mapping one name to one IPv4 address, such as fs-01.jahez.local to 10.10.60.20.
A switch port belonging to one VLAN, carrying plain untagged frames to a single device such as a PC or a printer, which never has to know a VLAN exists.
A recorded, dated check of who holds which permissions and what was decided about each, kept as evidence that a stated review policy is actually being carried out, not merely written down.
The switch a desk plugs into directly, such as the floor switches at Trio Complex HQ, as opposed to the distribution switch further up.
The set of VLANs a trunk link is configured to carry. A VLAN left off the list is silently dropped at that link even though it exists correctly on both switches, which is a common cause of one floor failing while another is fine.
A data-mining family that flags a value unlike its neighbours, such as one warranty date eight years out when nothing else is. The value is not impossible, only unusual, which is what makes it worth opening the record rather than deleting or accepting it.
Four datasets, built in 1973, that share an identical mean, standard deviation and correlation while looking completely different when actually plotted. The lesson: summary statistics can be identical across wildly different distributions, so plot the data before trusting the summary.
The 169.254.x.x address a Windows PC gives itself when it sent a DHCP Discover and heard no reply. It proves the network card and driver worked well enough to ask; the fault is somewhere in the DHCP path, not the card.
The five stages a tracked asset passes through: acquire, deploy, operate, maintain, and retire and dispose. Disposal is the stage that leaves the least evidence unless someone deliberately makes it, such as a wipe certificate and a closed record with a disposal date.
A data-mining family that looks for things that turn up together, such as discovering two fields are always filled in by the same person on the same afternoon, which is a fact about the process rather than the fleet.
One or more discrete data centres with their own power and networking, within roughly 100 km of the other zones in the same region. A subnet lives in exactly one availability zone, which is why subnet design is availability design.
A separate, restorable copy of data, distinct from high-availability replication: replication copies a mistake (such as a dropped table) at the same speed it copies everything else, so a replica is not a backup.
Judging a subgroup's failure count without knowing the size of the group it came from, so a brand with 14 of 20 failures is not necessarily unreliable if it is also three quarters of the whole fleet.
A record of what normal looks like, kept so that when something breaks you can tell what actually changed rather than guessing.
A method that starts at the cable and works upward through link, VLAN, address, gateway, name and application. Best when one user or one port fails and the physical layer is the likely suspect.
An account, such as AWS root, reserved for situations where every other form of access has failed, for example an admin having locked everyone out. It must carry MFA and should not be used for routine work.
The last address in a subnet, such as 10.10.60.255, which reaches every host in that subnet and which no single host may be assigned.
The set of ports a broadcast frame can reach. One VLAN is one broadcast domain, so a broadcast storm in one VLAN never touches another.
The risk created when the same rule (such as a discount calculation) is written independently in two places, for example inside an app's screen logic and again inside a flow; nothing keeps the two copies in sync, so a change to one silently disagrees with the other.
A value computed once, at refresh, and stored on every row of a table, used for anything that has to sit on an axis, in a slicer, or in a legend. It does not respond to a click.
A short classification recorded against an exception when two systems disagree, explaining why rather than editing either side into silent agreement, which would destroy the evidence of what happened.
A copy of a page or asset held by a caching layer in front of the origin server, controlled by cache-control headers such as max-age, which is why a freshly deployed change can still show stale content to visitors for a while.
A planned modification to a service, needing approval before anyone touches it. The test: is the current behaviour deliberate? “Can you set the timeout to one hour” is a change, not an incident.
Whoever is assigned to approve a given type of change; ITIL 4 does not mandate a single change advisory board, it says assign an authority per change type so it can be delegated, peer reviewed or automated.
A field restricted to a short, fixed list of values, replacing free text that would otherwise be typed as several different spellings of the same idea ("high", "High priority", "URGENT").
A data-mining family that learns a rule from examples that have already been labelled, the opposite of clustering, which finds its own groupings with no labels supplied.
A dataset is clean when it is consistent (one format, one convention throughout), complete enough (the fields you will actually analyze are filled), and traceable (you can say where it came from and when). Most things people call “data problems” are really consistency problems, and those are also the most fixable.
A data-mining family that groups records by how they behave, such as by age and model, without being handed the groups in advance; you decide afterward whether the groupings it found actually mean anything.
A written record of source, method, date, what was asked for, what came back, what was missing and why, and what was assumed. A dataset with no log cannot be trusted by anyone who was not there to watch it get built.
Any component that needs to be actively managed in order to deliver a service. It is defined by needing to be managed, not by its purchase price.
A third factor that drives two measurements at once, making them rise and fall together without either causing the other, such as a hiring cycle driving both password resets and printer ink orders every August.
The seven-step cycle: what is the vision, where are we now, where do we want to be, how do we get there, take action, did we get there, how do we keep the momentum. Skipping step two (a baseline) means step six becomes an opinion rather than a measured answer.
An agreed, short, fixed set of allowed values for a field (for example a status column limited to Deployed, In Stock, Retired) that is then locked so new free-text values cannot be typed in, stopping the same idea being spelled several different ways.
Two numbers moving together, however strongly, is not proof that one causes the other. Establishing cause needs a controlled comparison or ruling out a shared driver, not a stronger-looking chart.
A written description of what a custom connector expects and what it returns, which is what actually turns a personal tool one person built into something a teammate can call; a working connector with no such description is not really usable by anyone else.
The single destination for anything suspected security: phishing, suspicious access, possible data exposure, suspected fraud, a device you think is compromised. There is no exception, and being wrong in that direction costs nothing.
A dashboard is a single page, pinned from one or more reports, that cannot be filtered or sliced; a report is built on one semantic model, has many pages, and can be filtered every way. Saying “dashboard” to a stakeholder when a filterable report is meant is how the wrong thing gets built.
Looking for a pattern nobody set out to find, as opposed to reporting, which answers a question that was already asked. “Which laptops are out of warranty” is a report; “devices from one batch fail at twice the rate” is mining.
A purpose-built table of every calendar day, contiguous and complete across whole years, used to filter every fact table at once. A column of real purchase dates cannot serve this role because real dates are sparse: a day nobody bought anything simply does not exist in that column.
The distinction between a document that describes a tool or system in general terms and one that gives the actual step the reader needs. A paragraph explaining what a CMDB module is in general decorates; a line saying which tab to record a serial in helps.
The address of a router interface, in the same subnet as a host, that the host sends to whenever the destination is outside its own subnet.
Something a system needs in order to work at all, such as a domain controller needing the hypervisor beneath it running, so that one failure quietly takes several other systems down with it.
A protocol in which a server hands a host an IP address, subnet mask, default gateway and DNS servers automatically, for a limited lease period.
A table of things that exist, filtered and grouped by but never summed, such as employees, departments, or locations.
A deliberately invoked response to a major, discrete failure, usually across regions, accepting a period of downtime already agreed in advance, as distinct from high availability, which is continuous and automatic.
A method that starts in the middle of the stack, usually a ping to the gateway, and lets the result decide which half of the problem to keep testing. Suits a vague or unclear symptom.
The service that turns a name such as fs-01.jahez.local into an address such as 10.10.60.20, so that people and applications can use names instead of numbers.
A DNS answer a machine has stored and keeps reusing for a while. Flushing it (ipconfig /flushdns) forces a fresh lookup, which is why that command sometimes fixes a site that has moved to a new server.
The ordinary kind of TLS certificate almost every site has. It proves only that the connection is encrypted and that whoever requested the certificate could prove control of the domain at issuance; it says nothing about the organization behind the site or the honesty of its content.
The four steps of a DHCP exchange: Discover, Offer, Request, Acknowledge.
A change with its own faster authorization route for something that must go in immediately, such as a failed server needing a fix that night. It is still authorized, just on a faster path than a normal change.
Handing an issue on with the facts you have already proven, rather than with a guess.
A workflow trigger that fires the moment something happens (such as a record being created), suited to work that has to react instantly rather than wait for a periodic check.
A table of things that happened, at a consistent grain, holding numbers to add up and keys pointing out to dimension tables.
One of seven groups the asset register's fields are organized into — identity, ownership, lifecycle, financial, contractual, location, status — each answering a different question for a different named consumer, and each measured for completeness on its own rather than averaged into one number.
Work that needs no human input and follows a fixed, repeatable trigger and sequence, such as a scheduled nightly comparison between two systems; distinct from a screen, which a person operates interactively.
The four dimensions of service management: organizations and people, information and technology, partners and suppliers, and value streams and processes, all surrounded by external PESTLE factors nobody controls directly.
When a measure becomes a target, it stops being a good measure. A merchant acceptance rate that is graded starts getting gamed (accept then cancel, quote inflated times, or go offline so no order can be refused) rather than staying an honest reading of anything.
Seven principles that apply across the whole framework: focus on value, start where you are, progress iteratively with feedback, collaborate and promote visibility, think and work holistically, keep it simple and practical, and optimize and automate.
Continuous, usually automatic protection so that a failure (such as one data centre going down) is not noticed by users, typically achieved with multiple availability zones.
Any device with a network address: a laptop, a printer, or a server.
The host machine that runs virtual machines. If the hypervisor stops, every virtual server running on it stops with it.
Infrastructure as a Service: raw compute, storage and network handed over, with the customer responsible for everything from the operating system upward, such as Amazon EC2.
Permissions with no permanent credentials attached, assumed by a user or a workload to get temporary credentials that expire on their own, which is why AWS recommends roles over long-lived access keys.
How many people or how important a business function is affected: high (a whole site, department or critical service, or money/reputation at risk), medium (a team), or low (one person). Judged separately from urgency.
Something that used to work and is now broken. The test: did this work yesterday?
Moving packets between two VLANs using a device, typically a layer 3 switch, that holds an interface inside each VLAN.
A command placed on an SVI that turns a DHCP Discover broadcast into a unicast aimed at the DHCP server, since a broadcast alone cannot cross a router into another VLAN.
Four numbers from 0 to 255, such as 10.10.10.51, that identify one host on a network.
A shared, reliable identifier used to link two datasets together, such as an employee ID rather than a name, since names repeat, change, and get typed inconsistently, and joining on them can silently assign one person's record to another.
A document written for the user who has the problem, in their own words, with the steps and what to do if they fail; a different document from an SOP, which is written for a colleague performing an internal procedure.
A problem that has been analyzed and is not yet resolved. Writing it down is what lets the desk apply the workaround in seconds instead of rediscovering it from scratch.
The routing destinations for a ticket: L1 service desk (password resets, approved access, known how-to answers), L2 technical support (endpoint faults, single-desk issues), and L3 enterprise systems and infrastructure (server/service faults, identity, network design). This is a different taxonomy from the Tier 1/2/3 fault layers taught for network troubleshooting in week 2 games; the two schemes use the same words for different things and are not interchangeable.
The period a host is allowed to keep an address before it must ask to renew it.
Each identity, human or machine, gets the minimum resources and authorizations it needs to do its job. “Each entity” includes machine identities such as an EC2 instance role or a Lambda execution role, not only people.
A hardware address burned into a network card, which a switch learns and uses to forward each frame only to the port that needs it.
A value recalculated live, in the filter context of whatever is on screen, so it changes when a slicer is clicked. Used for anything that has to respond to interaction, such as a total or a percentage.
The set of records a collection effort could not answer for, with a reason recorded against each row where one is known. Reported separately from a plain hit count, since 562 matches out of 574 attempted still leaves 53 unaccounted for once the 41 that had no serial to look up at all are counted too.
The tendency for an employee who changes role or team to keep their old access alongside their new access, because the new grant is actively requested while nobody is watching to remove the old one, which an access review exists to catch.
A labelled step inside a Power Query cleaning pipeline that records what it does, so the query itself becomes documentation. An unnamed step documents nothing to whoever reads it back later, including the person who wrote it.
The one VLAN on a trunk that is sent untagged. It must match at both ends of the trunk, or traffic silently lands in the wrong VLAN.
A subnet-level, stateless filter that can both allow and deny traffic and is evaluated in rule-number order, unlike a security group, which only allows and automatically permits return traffic.
The four-page 2011 US government document that defines IaaS, PaaS and SaaS, and that every auditor and RFP still falls back on, despite predating serverless computing and having no model that covers it.
A change that is not pre-authorized and not an emergency, going through the change authority for that type before it is made.
Dividing a raw count by a period or population before comparing it, such as tickets per week rather than raw ticket totals, so that periods or groups of different size or length can be compared fairly.
The destination for a request that genuinely belongs to Facilities, HR or Finance. It has to be handed over properly, with a name and a reference, not closed silently.
The baseline, no-commitment price for cloud compute, paid only for what actually runs; right for spiky, short-lived or unpredictable workloads.
What a deliverable makes possible for the person receiving it, as distinct from the output, which is the thing itself. A shared mailbox is the output; replying to customers faster is the outcome.
The literal thing handed over, as distinct from the outcome it enables.
The two things a document needs at its header before anyone will risk trusting and following it: who is accountable for it, and when it was last confirmed still accurate. Missing either one, people ask a person instead of trusting the document.
The median (p50) and the value that 90 percent of observations fall under (p90) of a distribution, reported alongside a mean because an average can sit flat while the tail people actually experience gets much worse.
Platform as a Service: a place to deploy code without choosing or patching the underlying operating system, such as AWS Elastic Beanstalk or App Runner.
Saudi Arabia's Personal Data Protection Law. Personal data such as employee names and phone numbers stays inside Jahez systems; it must not be emailed to a personal address or copied to removable media to work on elsewhere, even for convenience.
Cleveland and McGill's 1984 finding that people read position along a common scale most accurately, then position on separate scales, then length and angle, then area, then colour last — the reason a sorted bar chart beats a pie chart for comparing categories.
The distinction between a message's display name, which is just typed text anyone can set to anything, and its actual sending domain, which is far harder to fake convincingly and is the detail that actually reveals a phishing attempt.
The physical socket on a switch that a cable plugs into, such as Gi1/0/12, as distinct from a service port such as 443.
About twenty records checked by hand, one at a time, against the source, run before a bulk import against live records. A hand check finds errors a spot check would miss; a smaller automated import does not.
The tool used to clean a dataset through a recorded, repeatable sequence of named steps rather than by hand-editing cells, so the same cleaning can be re-run automatically on next month's export.
ITIL 4 groups 34 practices into three categories: 14 general management, 17 service management, 3 technical management. ITIL Version 5 keeps the same 34 practices but regroups them into two categories.
The value calculated from impact and urgency together, never chosen directly. P1 is critical (a site, department or critical service down, or money/reputation at risk now); P5 is planning work with no clock on it.
Repeated incidents that share one cause, raised by IT rather than by a user. The test: have we fixed this exact thing before?
The rule that when a shaded area on a chart stands for a number, the area drawn has to be proportional to that number. A bar chart with a truncated axis breaks this rule and can turn a small real difference into what looks like a collapse.
The original, untouched export file kept aside as the evidence of what the data looked like before any cleaning. Editing it directly destroys the ability to prove what changed.
Comparing two systems that each hold a record of the same population, classifying every exception with a cause code, and leaving the two sides unedited so the disagreement stays visible rather than being erased.
A named geographic area, such as Bahrain or the UAE for AWS in the Middle East, made up of multiple availability zones. A CDN edge location is not a region: it caches content near users but does not durably store data.
An extreme result (such as the single worst-performing team in a month) tends to drift back toward average on its own, which can look identical to an intervention having worked unless there is a comparison group that received no intervention.
A data relationship where both sides can hold several of the other, such as a student enrolled in several courses while each course holds several students, requiring a different design than a simple one-to-many link.
A data relationship where one record on one side (such as a vendor) can relate to several records on the other side (such as purchase orders), while each of those relates back to exactly one vendor. The most common relationship shape in a real system.
An older AWS commitment mechanism tied to a specific instance configuration for one or three years, superseded in guidance by the more flexible Savings Plan.
Distortion in a survey or feedback channel caused by who chooses to respond, such as a satisfaction pop-up drawing disproportionately from people who are already annoyed.
Two different statuses in the asset register: Retired means withdrawn from service and still physically held; Disposed means gone, with a disposal record. Collapsing the two together is how a fleet count stops meaning anything.
The possibility that a correlation runs the opposite direction to the one first assumed, such as teams that already trust a process logging more tickets (rather than logging more tickets making people happier).
A file stating a site's own preference about automated access. Nothing technically enforces it, which is exactly why it matters: ignoring it is a decision that is on the record afterward.
The job a server performs, such as DNS, DHCP, Active Directory or file sharing, as distinct from the service, which is the program actually running that job.
The list a router checks in order to decide which interface a packet should leave by.
A document written for whoever is awake and on call while something is actively broken: ordered checks, no theory, ending with who to escalate to and how.
Software as a Service: a finished, working application handed to a business user, such as Amazon Connect, with nothing for the customer to patch or manage.
A certificate warning that occurs when the hostname in the browser's address bar is not among the names the certificate's subject and subject alternative names actually cover, a different failure from an expired certificate.
A one- or three-year commitment to a spending rate per hour of compute (not to a specific instance type), giving up to about 72 percent off on-demand pricing while staying flexible across instance family, size, OS and region.
An interactive surface a person operates directly, used for a repeated task that differs every time (browsing, filtering, editing); distinct from a report, which is read only, and a flow, which runs on its own with no interaction.
An instance-level, stateful firewall in AWS: it remembers a connection it allowed and automatically permits the reply, unlike a network ACL, which has no memory of a connection.
Splitting one physical switch into several separate networks to limit broadcast noise and control which groups of devices can reach each other.
A request resolved before it ever reaches the service desk, such as a user resetting their own password through a portal. It counts as a real resolution, and every request that never reaches L1 is capacity L1 gets back.
The current name for what used to be called a dataset in Power BI (the rename is deliberately incomplete: the REST API, activity log and paginated reports still say dataset).
Data that carries its own keys, such as JSON, so a machine can navigate it, but whose exact shape is not guaranteed to repeat row to row — a field that is only present sometimes has to be handled rather than assumed.
The principle that the person requesting something and the person approving it must be different people, so that a self-approval, even if logged, cannot happen.
A means of enabling value co-creation by facilitating outcomes customers want, without the customer having to manage specific costs and risks themselves. This is a different sense of the word “service” from the Windows/technical background program taught in week 2 (a role such as DNS or DHCP); the two are unrelated meanings of the same word.
The background program that actually runs a role. A server can be fully powered on and answering ping while a single stopped service means it delivers nothing at all.
A description of one or more services designed for a target consumer group, which can bundle goods, access to resources, and service actions.
Something a person wants that is normal, agreed and predefined, such as access from a catalogue. The test: did they ever have it? Urgency does not turn a request into an incident.
An operating model, not a fixed process: six activities (plan, improve, engage, design and transition, obtain/build, deliver and support) with no fixed order, since Plan and Improve run continuously and any real piece of work follows its own path through the rest.
The whole system that turns opportunity and demand into value, made of five components: guiding principles, governance, the service value chain, the practices, and continual improvement.
A login used by more than one person. Every action it takes lands in a log against one name that is not a person, so nobody can say afterward who was actually at the keyboard for a given action.
AWS's split between “security of the cloud” (AWS's job: physical security, the hypervisor) and “security in the cloud” (the customer's job: the operating system, data, identity and configuration). The exact line moves depending on the service chosen, but the customer's data, identity and configuration never move off the customer's side.
A pattern where a trend appears in every subgroup of data but reverses or disappears when the subgroups are pooled together, because the groups differ in some other way that pooling hides.
One item whose loss takes several dependent systems down at once, such as a hypervisor with no second hypervisor behind it.
The protocol Windows uses to serve file shares.
Server Name Indication: the part of the TLS handshake where the browser states, in plain text, which hostname it wants before encryption is agreed, which is what lets one IP address host many independent HTTPS sites, each with its own certificate.
A discipline for finishing an analysis: state the observation, say what it means, and name an action with an owner and a date attached. If the chain cannot reach an owner and a date, the metric being reported is probably the wrong one.
A Standard Operating Procedure: a repeatable procedure written for a colleague who has not done the task before, with an owner, a last-reviewed date, prerequisites, one numbered action per step, how to confirm success, and an escalation path.
Two facts that must be recorded beside any field: where the value came from, and what keeps it true afterward (such as a scheduled re-run). A field with a source but no refresh path goes stale within a quarter with nothing to flag it.
AWS compute offered at up to about 90 percent off on-demand price, with the trade-off that AWS can reclaim the instance when it needs the capacity back; suited only to work that can be interrupted and restarted.
A DNS entry naming which server offers a particular service, used by Active Directory clients to locate a domain controller. No answer here means no domain controller found, so logon fails even though the file server itself may be fine.
A change that is pre-authorized once as a type, low risk, and follows a known procedure, so it does not need approval repeated every time it recurs.
Data where a header row is a contract: every row means the same thing in the same column, such as a Jira Assets export with identical columns throughout.
The value that marks which part of an IP address is the network and which part is the host, and so decides whether a destination is local or has to be routed.
A virtual interface on a layer 3 switch that holds the default-gateway address for one VLAN.
An explicit rule saying which system wins per field when two systems disagree, so a disagreement becomes a difference list somebody works through rather than the more recently edited value silently winning with no record of whose it was.
The one system authoritative for a given field, decided per field rather than per asset — for example Intune owns last check-in, the asset register owns assignment and status, and Finance owns cost and net book value.
In the Ops Range and its game, the three layers a network fault can live at: Tier 1 the access layer (cable, port, VLAN), Tier 2 routing, DHCP and DNS, and Tier 3 servers and services. This is a different scheme from the L1/L2/L3 support-routing tiers taught in week 3; see the note under L1/L2/L3.
A workflow trigger that runs on a recurring schedule rather than reacting to a single event, suited to conditions that accumulate over time (such as an invoice sitting unpaid past a threshold) rather than to one moment.
A method that starts at the application and works downward through the same layers as bottom-up. Best when the lower layers are already proven, for example when everyone else on the network is fine.
A switch port that carries several VLANs over one cable between switches, tagging each frame with the VLAN it belongs to.
The time a DNS answer may be cached by a resolver before it must be checked again. A record changed right now is not reliably seen everywhere until the old TTL has fully expired.
A DNS record added to prove control of a domain to a third-party provider (for example before it will send mail as that domain or issue it a certificate); it proves DNS control at that moment, nothing about the site's safety or billing.
The honest way to report a gap between two systems counting overlapping but different populations (for example roughly 843 Windows devices in Intune against 615 laptops in the asset register) before every row has been given a cause code, rather than calling the raw gap "missing assets."
Data with no fixed shape at all, such as a sentence in an email that happens to mention three asset tags. The label describes the container, not the value of what is inside it; the tags themselves are perfectly good data sitting somewhere no report will reach.
The cable joining an access switch to the distribution switch above it.
How fast a ticket must move: high (work stopped now, or a same-day deadline), medium (degraded, with a workaround), or low (can wait). Judged separately from impact.
Three roles in a service relationship that can be held by one person or split across several: the user uses the service, the customer defines requirements and agrees outcomes, and the sponsor authorizes the budget.
What a service does; whether it is fit for purpose. Paired with warranty, which is how well it does it.
The outcome achieved minus the costs and risks the consumer is left carrying. A cheap service that leaves the user doing a manual workaround has reduced value, because the workaround is a cost the user still carries.
A path through the service value chain defined once for one type of work; not a seventh activity, and not redrawn for every ticket. Different kinds of work take different paths through the same six activities.
The destination for a system a third party runs and Corporate IT does not. The ticket and its updates are still owned internally even while the fix itself sits with the vendor.
A group of switch ports configured to behave as their own separate network and broadcast domain, letting one physical switch carry several logically separate networks.
The number, from 1 to 4094, that identifies a VLAN on a switch.
Deliberately keeping historical copies of a live system's state, taken as a decision before the period you will need them, since a live register only ever answers what is true now, and a backup restores a system rather than giving you a series to report on.
How well a service performs: whether it is available, capable, secure and continuous enough. Paired with utility, which is what the service does.
Two ways to lay out the same data: wide puts one column per category (for example one column per month), long puts one row per observation with a category column. Long is the shape a chart, a pivot or a database wants; wide is for reading on paper.
A way to reduce or remove the impact of a problem while its underlying cause is still there, such as rebooting a machine or using a different printer. It does not remove the cause, and some workarounds stay in place permanently when fixing the cause is not worth the cost.
The bare root of a domain (example.com with no www). It always carries an SOA and NS record, so it can never also carry a CNAME record, which is why the bare domain sometimes needs a plain A/AAAA record instead of a CNAME.
This page is not yet linked from anywhere else in the lab. It was built as a standalone reference, the same way design.html is, and it is deliberately not wired into index.html, games.html or any week page, because those are being edited elsewhere at the same time this page was built. It belongs on the main navigation alongside the desk reference, and a "see also" link from desk-reference.html and from each week's path.html and exam.html page back to the specific letter here would close the loop the teach skill asks for: lessons and reference documents linking to each other.