Questions and Answers
What is the primary function of a recursive DNS server?
What type of DNS record maps an alias or alternate name to a canonical name?
What is the primary purpose of DNSSEC?
What type of attack involves a fake DNS server returning a fake IP address?
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What is the purpose of a DNS cache?
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What type of DNS record maps a domain name to an IP address?
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What is the purpose of the TTL in DNS caching?
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What is the type of DNS server that holds the DNS records for a specific domain name?
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The process of DNS resolution involves only two stages.
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Authoritative DNS servers cache DNS records to speed up resolution.
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Root DNS servers are responsible for specific domain names.
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DNS resolution always involves querying the root DNS servers.
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The main purpose of DNS cache is to slow down future requests.
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DNS resolution is the process of translating an IP address into a domain name.
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A CNAME record maps an IP address to a domain name.
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DNSSEC is a security protocol that uses digital signatures to authenticate DNS records.
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The operating system cache is responsible for caching DNS records to speed up page loading.
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DNS amplification attacks use DNS servers to reduce traffic in a DDoS attack.
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A PTR record maps a domain name to an IP address.
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The browser cache is responsible for caching DNS records to speed up DNS resolution.
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Study Notes
DNS Resolution
- The process of translating a domain name into an IP address
- Involves a series of queries to DNS servers to resolve the domain name
- Steps:
- Browser cache: Check browser cache for the IP address
- Operating system cache: Check OS cache for the IP address
-
Local DNS resolver: Send query to local DNS resolver (e.g.
/etc/hostsfile) - Recursive DNS server: Send query to recursive DNS server (e.g. ISP's DNS server)
-
Root DNS server: Send query to root DNS server (e.g.
.) -
TLD DNS server: Send query to TLD DNS server (e.g.
.com) - Authoritative DNS server: Send query to authoritative DNS server (e.g. domain's DNS server)
- IP address: Receive IP address from authoritative DNS server
DNS Servers
- Recursive DNS server: Resolves domain names recursively, starting from the root DNS server
- Authoritative DNS server: Holds the DNS records for a specific domain name
- Caching DNS server: Caches DNS records to reduce the load on recursive DNS servers
- Proxy DNS server: Acts as an intermediary between clients and DNS servers
- DNS forwarder: Forwards DNS queries to another DNS server
DNS Records
- A record: Maps a domain name to an IP address
- AAAA record: Maps a domain name to an IPv6 address
- CNAME record: Maps an alias or alternate name to a canonical name
- MX record: Maps a domain name to a mail server
- NS record: Maps a domain name to a name server
- PTR record: Maps an IP address to a domain name (reverse DNS)
- SOA record: Specifies the start of authority for a DNS zone
- TXT record: Holds text information about a domain
- SRV record: Maps a service name and protocol to a domain name and port number
DNS Security
- DNS spoofing: Attack where a fake DNS server returns a fake IP address
- DNS cache poisoning: Attack where a fake DNS record is injected into a DNS cache
- DDoS attacks: Attack where a large volume of DNS queries are sent to overwhelm a DNS server
- DNSSEC: A security protocol that authenticates DNS data and ensures its integrity
- TLS/SSL certificates: Used to encrypt DNS traffic and ensure authenticity
DNS Cache
- Browser cache: Stores DNS records in the browser's cache
- Operating system cache: Stores DNS records in the OS's cache
- DNS cache server: Stores DNS records to reduce the load on recursive DNS servers
- TTL (Time To Live): Specifies how long a DNS record is cached
- Cache poisoning: Attack where a fake DNS record is injected into a DNS cache
DNS Resolution
- Translates a domain name into an IP address through a series of queries to DNS servers
- Involves 8 steps: browser cache, OS cache, local DNS resolver, recursive DNS server, root DNS server, TLD DNS server, authoritative DNS server, and receiving the IP address
DNS Servers
- Recursive DNS server: Recursively resolves domain names starting from the root DNS server
- Authoritative DNS server: Holds DNS records for a specific domain name
- Caching DNS server: Caches DNS records to reduce load on recursive DNS servers
- Proxy DNS server: Acts as an intermediary between clients and DNS servers
- DNS forwarder: Forwards DNS queries to another DNS server
DNS Records
- A record: Maps a domain name to an IP address
- AAAA record: Maps a domain name to an IPv6 address
- CNAME record: Maps an alias or alternate name to a canonical name
- MX record: Maps a domain name to a mail server
- NS record: Maps a domain name to a name server
- PTR record: Maps an IP address to a domain name (reverse DNS)
- SOA record: Specifies the start of authority for a DNS zone
- TXT record: Holds text information about a domain
- SRV record: Maps a service name and protocol to a domain name and port number
DNS Security
- DNS spoofing: Attack where a fake DNS server returns a fake IP address
- DNS cache poisoning: Attack where a fake DNS record is injected into a DNS cache
- DDoS attacks: Attack where a large volume of DNS queries are sent to overwhelm a DNS server
- DNSSEC: A security protocol that authenticates DNS data and ensures its integrity
- TLS/SSL certificates: Used to encrypt DNS traffic and ensure authenticity
DNS Cache
- Browser cache: Stores DNS records in the browser's cache
- Operating system cache: Stores DNS records in the OS's cache
- DNS cache server: Stores DNS records to reduce load on recursive DNS servers
- TTL (Time To Live): Specifies how long a DNS record is cached
- Cache poisoning: Attack where a fake DNS record is injected into a DNS cache
DNS Resolution
- DNS resolution involves translating a domain name into an IP address through a series of requests and responses between DNS clients, resolvers, and DNS servers
- The process occurs in three stages: recursive resolution, authoritative resolution, and cache resolution
DNS Resolution Stages
- Recursive resolution: A DNS client queries a recursive DNS resolver, which then queries other DNS servers to resolve the domain name
- Authoritative resolution: The recursive resolver receives the IP address from an authoritative DNS server, responsible for the domain name
- Cache resolution: The recursive resolver caches the resolved IP address to speed up future requests
DNS Servers
- Recursive DNS servers (caching DNS servers) cache DNS records to speed up resolution
- Authoritative DNS servers are responsible for specific domain names and provide actual DNS records
- Root DNS servers are the highest level, responsible for the root zone (.) and delegating requests to top-level domain (TLD) servers
- TLD DNS servers are responsible for specific TLDs (e.g., .com, .org)
DNS Records
- A record: Maps a domain name to an IP address
- CNAME record: Maps an alias or alternate name to a canonical name of a server or host
- MX record: Maps a domain name to a mail server
- NS record: Maps a domain name to a name server
- PTR record: Maps an IP address to a domain name (reverse DNS)
- TXT record: Holds text information about a domain
- SOA record: Specifies the start of authority for a DNS zone
DNS Security Threats
- DNS spoofing: Attackers intercept DNS queries and return fake DNS records
- DNS cache poisoning: Attackers inject fake DNS records into a cache to redirect users to malicious sites
- DNS amplification attacks: Attackers use DNS servers to amplify traffic in a DDoS attack
DNS Security Measures
- DNSSEC: A security protocol that uses digital signatures to authenticate DNS records and prevent spoofing
DNS Cache
- Browser cache: Web browsers cache DNS records to speed up page loading
- Operating system cache: The operating system caches DNS records to speed up DNS resolution
- DNS resolver cache: Recursive DNS resolvers cache DNS records to speed up resolution
- Time to live (TTL): The time period for which a DNS record is valid in the cache
- Cache invalidation: The process of updating or removing cached DNS records when they expire or change
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Description
Learn the steps involved in translating a domain name into an IP address, from browser cache to root DNS servers.
