S11-Network Services Flashcards
What is DHCP?
“Dynamic Host Configuration Protocol”
Provides an IP address to every device on the network
What is a Scope?
A list of Valid IP Addresses available for assignment or lease.
DHCP Reservation
Excludes some IP Addresses from being handed out to devices unless a condition is met.
What is DORA
4-step process of a device acquiring an IP address information from a DHCP server
What does each letter of D.O.R.A mean?
-Discover
- Offer
- Request
- Acknowledge
Average Lease times for Home and Corporate networks.
Home
- 24 hours
Corporate
- 7 or 30 days
What 4 pieces of IP information does a device receive when configured through DHCP?
- IP Address
- Subnet Mask
- Default Gateway IP
- DNS Server IP
What 4 components can be configured as part of your scope?
- Subnet Mask
- Default Gateway
- DNS Server
- lease Time
What is a DHCP Relay?
host that Forwards DHCP packets between clients and servers
When do you need a DHCP relay?
when the client device and the DHCP server are not located on the same subnet/network
What Transport Protocol does DHCP use?
UDP
What is an IP Helper?
An IP helper address on a router configures it to act as a relay agent, forwarding UDP broadcast messages (like DHCP requests) to a designated host, typically a DHCP server, on a different subnet
What is SLAAC
“Stateless Address Autoconfiguration”
IPv6 network protocol that simplifies the network configuring process w/o the need for a DHCP
Benefits of SLACC?
- Enhance Efficiency of networks
- Mitigate IP Conflicts
- Streamline device network configuration process
What is the 5 step process for SLAAC?
1 - Device Initiation
2 - Router Solicitation
3 - Router Advertisement
4 - Address Configuration
5 - Final Check
Device Initiation
1st step of SLAAC
A Connecting device generates a temp. link local address
Router Solicitation
2nd Step of SLAAC
Device sends a message on the network requesting router locations
Router Advertisement
3rd Step of SLAAC
Routers on the network respond to the RS inquiry, sending back an Advertisement message with network prefix
Address Configuration
4th Step of SLAAC
Device will combine the network prefix with its own unique identifier
Final Check
5th Step of SLAAC
Device performs a neighbor solicitation to ensure its IP address is unique
what is DNS
“Domain Name System”
Resolves IP’s into names and vice versa
What is an FQDN?
‘Fully Qualified Domain Name”
A domain name that is under a top-level provider
What are Top-level domains (TLDs)?
The extensions at the end of a domain name, like “.com” or “.org”.
TLDs help categorize websites and are used to organize the internet’s domain structure.
How is a FQDN Structured?
www.example.com
Comprised of:
- A sub-domain : “www.”
- A second level domain; “example”
- A Top level domain: “.com”
What are the 5 different levels in the DNS hierarchy?
- Root
- Top-Level Domain
- Second-Level Domain
- Subdomain
- Host
Root Level Domain
Highest level which answers requests in the root zone.
The root domain is the foundation upon which subdomains, subfolders, and individual pages are built.
- eg. “example.com”
Second - Level Domains (SLDs)
the part of a domain name that appears immediately before the top-level domain
The SLD often represents the primary domain or brand name of a website.
- eg. “example” in example.com is the SLD
Sub Domain
a section of a website identified by a unique prefix added to the main domain name
Subdomains help organize content and create distinct sections of a website without having to set up a completely new domain.
- eg. “www.” , “blog.” , “shop.”, “Mail.”
Host Level
identifies a specific device, often a server, within a network
What are the 2 types of TLDs?
Organizational: .com, .NET, .org
Geographical: .uk, .it, .fr
What is a URL?
“Uniform Resource Locator”
Contains the FQDN with the method of accessing information
What is a Host File?
a plain text file used by an operating system to map hostnames to IP addresses.
It acts as a local DNS for your machine, allowing you to manually specify how certain hostnames should be resolved, potentially overriding the system’s default DNS settings.
What are the DNS record types?
- A
- AAAA
- CNAME
- MX
- SOA
- PTR
- TXT
- NS
A Record
“Address Record”
Links a hostname to an IPv4 Address
AAAA record
Links a hostname to an IPv6 Address
CNAME Record
“Canonical Name”
Points a domain to another domain/subdomain. does not point to IP addresses
MX Record
“Mail Exchange”
Directs emails to a mail server. does not point to an IP
SOA Record
“Start of Authority”
Stores information about a domain or zone
PTR Record
“Pointer Record”
Correlates an IP with a Domain name, Reverse DNS
TXT Record
“Text Record”
Adds text into the DNS
NS Record
“NameServer Record”
indicates which DNS nameserver has authority
What is a Zone transfer?
DNS records are sent from the primary nameserver to a secondary nameserver
- Uses TCP
How are Pointer Records usually stored?
Under the .arpa Top level domain
eg. “ 33.44.55.66.in-addr.arpa”
What is ARPAnet?
“Advanced Research Projects Agency Network”
the first public packet-switched computer network serving as a foundation for the modern internet. (1969 - 1989)
Forward Lookup
Uses DNS to find IP address for a domain name
Reverse Lookup
Uses DNS to find a domain name for an IP address
what is a Name Server?
DNS server that stores all the records for a given Domain. usually threes a primary and secondary nameserver
Internal DNS
Allows cloud instances on the same network access each other using internal DNS names
External DNS
Records created around domain names from a central authority and used on the public internet
What is Time to Live (TTL)?
Tells the DNS resolver how long to cache a query before requesting a new one
DNS Resolver/DNS Cache
Makes a local copy of every DN entry it resolves as the user connect to website
Where is the DNS Resolver located?
On your individual Host within the browser or Operating system
Recursive Lookup
DNS server communicates with other DNS servers to find an IP address
Iterative Lookup
a process where a DNS client makes a series of requests to different DNS servers to find the IP address of a domain name.
What are some DNS security measures?
- DNS Security Extensions
- DNS over HTTPS
- DNS over TLS
DNS Security Extensions (DNSSEC)
Provides a digital tamper-proof seal for the DNS data to ensure that the information reaching the device is exactly what the server intended to send
T/F: DNSSEC encrypts DNS data.
False
DNS over HTTPS (DoH)
DNS queries are sent through the HTTPS protocol, and encrypts your DNS data
DNS over TLS (DoT)
Encapsulates DNS traffic inside of a transport layer security tunnel, and encrypts DNS data.
- protects against DNS snooping
what is DNS Snooping?
An attack where the attacker monitors DNS queries to infer what website a user is visiting
