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Questions and Answers
What is the primary function of DNS resolution?
What is the primary function of DNS resolution?
Which type of DNS record is used to map an alias or alternate name to a canonical name?
Which type of DNS record is used to map an alias or alternate name to a canonical name?
What is the purpose of a DNS resolver?
What is the purpose of a DNS resolver?
What is the term for injecting fake DNS records into a cache to redirect users to fake websites?
What is the term for injecting fake DNS records into a cache to redirect users to fake websites?
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What is the primary goal of DNSSEC?
What is the primary goal of DNSSEC?
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What is the purpose of a TTL in DNS caching?
What is the purpose of a TTL in DNS caching?
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What type of DNS record is used to route email to a mail server?
What type of DNS record is used to route email to a mail server?
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What is the main purpose of a PTR record in DNS?
What is the main purpose of a PTR record in DNS?
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What is the term for the process of registering a domain name with a registrar?
What is the term for the process of registering a domain name with a registrar?
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What is the primary function of DNS caching?
What is the primary function of DNS caching?
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What is the purpose of an SRV record in DNS?
What is the purpose of an SRV record in DNS?
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What is the effect of updating DNS records on cache entries?
What is the effect of updating DNS records on cache entries?
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What determines how long DNS records remain in the cache?
What determines how long DNS records remain in the cache?
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What is the main goal of the recursive DNS resolver in the DNS resolution process?
What is the main goal of the recursive DNS resolver in the DNS resolution process?
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What is stored in a WHOIS database?
What is stored in a WHOIS database?
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Which of the following is a security measure to mitigate DDoS attacks on DNS servers?
Which of the following is a security measure to mitigate DDoS attacks on DNS servers?
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What type of DNS record is used to specify the name servers responsible for a domain?
What type of DNS record is used to specify the name servers responsible for a domain?
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What is the purpose of DNS over TLS (DoT) and DNS over HTTPS (DoH)?
What is the purpose of DNS over TLS (DoT) and DNS over HTTPS (DoH)?
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What is the first step in the DNS resolution process?
What is the first step in the DNS resolution process?
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What is the threat of cache poisoning in DNS?
What is the threat of cache poisoning in DNS?
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What is the purpose of a DNS resolver in a browser or OS?
What is the purpose of a DNS resolver in a browser or OS?
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Study Notes
DNS Resolution
- The process of translating a domain name into an IP address
- Involves a series of requests between DNS servers to find the authoritative name server for a domain
- Steps:
- Browser or application sends a request to a DNS resolver (usually provided by the operating system or ISP)
- DNS resolver sends a request to a root DNS server
- Root DNS server responds with the address of a top-level domain (TLD) DNS server
- DNS resolver sends a request to the TLD DNS server
- TLD DNS server responds with the address of the authoritative name server for the domain
- DNS resolver sends a request to the authoritative name server
- Authoritative name server responds with the IP address associated with the domain name
DNS Record Types
- A records: map a domain name to an IP address
- NS records: identify the name servers responsible for a domain
- MX records: route email to a mail server
- CNAME records: map an alias or alternate name to a canonical name
- PTR records: map an IP address to a domain name (reverse DNS)
- TXT records: hold text information about a domain
- SOA records: specify the start of authority for a DNS zone
- SRV records: specify the location of services such as LDAP or SIP
DNS Security
- DNS spoofing: intercepting and altering DNS requests to redirect users to fake websites
- DNS cache poisoning: injecting fake DNS records into a DNS cache to redirect users to fake websites
- DNSSEC (Domain Name System Security Extensions): adds digital signatures to DNS records to ensure authenticity and integrity
- DNSSec validation: verifies the digital signatures of DNS records to ensure they come from the authoritative name server
DNS Caching
- DNS resolvers and DNS servers cache DNS records to improve performance and reduce latency
- Cache TTL (Time To Live): specifies how long a DNS record can be cached before it expires
- Cache poisoning: injecting fake DNS records into a cache to redirect users to fake websites
- DNS caching can be implemented at the browser, operating system, or ISP level
Domain Registration
- The process of registering a domain name with a registrar (e.g. GoDaddy, Namecheap)
- Domain registrars are accredited by ICANN (Internet Corporation for Assigned Names and Numbers)
- Registration information is stored in a WHOIS database
- Domain registration typically includes:
- Registrant contact information
- Administrative contact information
- Technical contact information
- Name servers for the domain
- Domain registration can be public or private (using WHOIS privacy services)
DNS Resolution
- DNS resolution is the process of translating a domain name into an IP address.
- It involves a series of requests between DNS servers to find the authoritative name server for a domain.
- The process starts with a browser or application sending a request to a DNS resolver.
- The DNS resolver sends requests to a root DNS server, then to a top-level domain (TLD) DNS server, and finally to the authoritative name server for the domain.
- The authoritative name server responds with the IP address associated with the domain name.
DNS Record Types
- A records map a domain name to an IP address.
- NS records identify the name servers responsible for a domain.
- MX records route email to a mail server.
- CNAME records map an alias or alternate name to a canonical name.
- PTR records map an IP address to a domain name (reverse DNS).
- TXT records hold text information about a domain.
- SOA records specify the start of authority for a DNS zone.
- SRV records specify the location of services such as LDAP or SIP.
DNS Security
- DNS spoofing is a type of attack where an attacker intercepts and alters DNS requests to redirect users to fake websites.
- DNS cache poisoning is a type of attack where an attacker injects fake DNS records into a DNS cache to redirect users to fake websites.
- DNSSEC (Domain Name System Security Extensions) adds digital signatures to DNS records to ensure authenticity and integrity.
- DNSSec validation verifies the digital signatures of DNS records to ensure they come from the authoritative name server.
DNS Caching
- DNS resolvers and DNS servers cache DNS records to improve performance and reduce latency.
- Cache TTL (Time To Live) specifies how long a DNS record can be cached before it expires.
- Cache poisoning is a type of attack where an attacker injects fake DNS records into a cache to redirect users to fake websites.
- DNS caching can be implemented at the browser, operating system, or ISP level.
Domain Registration
- Domain registration is the process of registering a domain name with a registrar (e.g. GoDaddy, Namecheap).
- Domain registrars are accredited by ICANN (Internet Corporation for Assigned Names and Numbers).
- Registration information is stored in a WHOIS database.
- Domain registration typically includes registrant contact information, administrative contact information, technical contact information, and name servers for the domain.
- Domain registration can be public or private (using WHOIS privacy services).
DNS Resolution
- DNS resolution is the process of translating a domain name into an IP address.
- It involves a series of requests between DNS servers to find the IP address associated with a domain name.
- The process includes:
- Recursive DNS resolver sending a query to a DNS recursive resolver.
- Recursive resolver querying a root DNS server to find the top-level domain (TLD) server associated with the domain.
- Recursive resolver querying the TLD server to find the authoritative DNS server for the domain.
- Authoritative DNS server returning the IP address associated with the domain.
- Recursive resolver returning the IP address to the original requester.
Domain Registration
- Domain registration is the process of registering a domain name with a domain name registrar.
- It requires choosing a domain name registrar, verifying domain ownership, providing contact information, and paying registration fees.
- Registration information is stored in a WHOIS database.
- Domain registration typically includes:
- Domain name.
- Registrant contact information.
- Name servers (DNS servers) responsible for the domain.
DNS Security
- Threats to DNS include:
- Cache poisoning (injecting false information into DNS caches).
- DNS spoofing (redirecting users to fake websites).
- DDoS attacks (overwhelming DNS servers with traffic).
- Security measures include:
- DNSSEC (Domain Name System Security Extensions) - adds digital signatures to DNS data to verify authenticity.
- DNS over TLS (DoT) and DNS over HTTPS (DoH) - encrypt DNS traffic.
- Rate limiting and IP blocking to mitigate DDoS attacks.
- Regularly updating DNS software and plugins to prevent vulnerabilities.
DNS Record Types
- Common DNS record types include:
- A record - maps a domain name to an IP address.
- NS record - specifies the name servers responsible for a domain.
- MX record - specifies the mail servers responsible for a domain.
- CNAME record - maps an alias or subdomain to a canonical domain name.
- PTR record - maps an IP address to a domain name (reverse DNS).
- TXT record - holds text information about a domain (e.g. SPF records).
- SRV record - specifies the location of services (e.g. LDAP or SIP).
DNS Caching
- DNS caching is the temporary storage of DNS query results to improve performance.
- Types of DNS caching include:
- Browser caching - stores DNS results in the browser's cache.
- Operating system caching - stores DNS results in the OS's cache.
- DNS resolver caching - stores DNS results in the DNS recursive resolver's cache.
- Authoritative DNS server caching - stores DNS results in the authoritative DNS server's cache.
- Cache expiration: DNS records have a time-to-live (TTL) that determines how long they remain in the cache.
- Cache invalidation: updating DNS records can invalidate cache entries, requiring a new DNS query.
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Description
Learn how domain names are translated into IP addresses through a series of requests between DNS servers.
