Network+ - 3.4 - 3.5

DHCP Process

Client does a broad search for DHCP server

DHCP then offers ip addresses

client then request one of the offered ips

then the DHCP server acknowledges the request

DHCP broadcasting

DHCP usually only broadcasts to subnets, to enable cross subnets use a dhcp helper

Domain Name System

translates readable names into ip addresses. is also used for the internet, active directory, and application access.

Primary DNS

The server that holds the original, editable copy of a zone’s records. TTL on authoritative server decides how long its valid for.

Secondary DNS

A server that holds a read-only copy, pulled from the primary.

local name resolution

overriding the dns server using the host file

forward/reverse lookup

provide name, dns gives ip. reverse is exact opposite

Recursive DNS query

a request where the client tells the DNS server: “Give me the final answer, or tell me it doesn’t exist. Do all the work yourself.”

Unsecured DNS

use DNS Security Extensions (DNSSEC) to authenticate results

use DNS over TLS (sends DNS traffic to port 853) for security

use DNS over HTTPS to secure over port 443

DNS Records

over 30 types of records of domain name services

Start of Authority

overview of DNS configuration file

Address records

(A) records map names to IPv4 addresses and AAAA records map names to IPv6 addresses

Canonical name record (CNAME)

Instead of mapping a name to an IP address like an A or AAAA record does, it maps a name to another name

Mail exchange (MX) record

tells the world which mail servers accept email for a domain.

text records

TXT records attach free-form text to a domain. In practice that text runs email authentication (SPF, DKIM, DMARC), domain ownership proofs, and certificate challenges.

name server records

names the authoritative name servers for a domain.

pointer record

A PTR record does the reverse of an A record: it maps an IP address → hostname.

service set identifier (SSID)

name of wifi

Basic SSID

hardware address of access point

Extended SSID

network name shared through access points

Captive Portal

authentication to a network