Question 1

What does DHCP actually do?

Accepted Answer

**Dynamic Host Configuration Protocol** hands out network settings automatically, so a device joining a network can configure itself without anyone typing anything.

**What it supplies.** Not just an IP address — the full set a device needs:

**An IP address** from a defined pool.

**A subnet mask.**

**A default gateway** — the router to send non-local traffic to.

**DNS server addresses.**

**Sometimes more** — NTP time servers, domain search suffixes, and configuration for IP telephones or network boot.

**How the exchange works**, conventionally remembered as **DORA**:

**Discover** — the client broadcasts a request, since it has no address yet and does not know where the server is.

**Offer** — a DHCP server responds with a proposed address.

**Request** — the client formally asks for that address, broadcast so any other servers know it declined theirs.

**Acknowledge** — the server confirms and records the assignment.

**Leases.** An address is not permanent; it is **leased** for a period. The client attempts renewal at around half the lease time, and again later. If it never renews, the address returns to the pool for reuse. This is what allows a network to serve far more devices over time than it has addresses.

**A DHCP reservation** ties a specific address to a device's **MAC address**, so it always receives the same one. This is almost always better than setting a static address on the device itself, because the router remains aware of the allocation and cannot hand it to something else.

**What goes wrong:**

**Two DHCP servers** on one network — typically a second router added without disabling its DHCP — producing conflicting addresses and intermittent failures. This is the single most common home network misconfiguration.

**Pool exhaustion**, where more devices than addresses appear.

**An address in the 169.254.x.x range** means the device gave up and self-assigned — the DHCP server was unreachable. It is a useful diagnostic, indicating a link or server problem rather than an internet problem.

**Static addresses set inside the DHCP pool**, causing conflicts.

Question 2

What is a MAC address, and how is it different from an IP address?

Accepted Answer

A MAC address identifies a piece of hardware on a local network; an IP address identifies a location on the internet. One is fixed to the device, the other describes where the device currently is —

Question 3

What is a subnet mask actually for?

Accepted Answer

It tells a device which part of an IP address identifies the network and which part identifies the host — and therefore whether a destination is local or has to go via the router. The decision it

Question 4

What is an internet exchange point?

Accepted Answer

A physical location where many independent networks connect to one another directly, rather than sending traffic through a chain of intermediaries. The problem it solves. Without exchanges, two

Question 5

What does a DNS server actually do?

Accepted Answer

A DNS server translates names people can remember into the numeric addresses machines actually use to route traffic. Every connection you make begins with a lookup, and if that lookup fails nothing

Question 6

Who actually runs the internet?

Accepted Answer

Nobody, and several bodies with narrow remits — which is the accurate answer rather than an evasive one. There is no central authority; there are institutions that coordinate specific scarce

Question 7

What is the difference between a static and a dynamic IP address?

Accepted Answer

Whether your public address stays the same or changes periodically — and for most people it matters far less than it sounds, until it suddenly matters a great deal. Dynamic. Your ISP assigns an

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