5.2 Domain name system management

The Domain Name System (DNS) is the internet's address book, translating human-friendly domain names into machine-readable IP addresses. It's a crucial part of internet infrastructure, enabling seamless navigation while raising important questions about governance and control.

DNS management involves a complex hierarchy of servers, various record types, and security measures. It intersects with policy issues like privacy, censorship, and trademark protection, highlighting the need for balanced approaches in technology governance.

Domain name system overview

• Domain Name System (DNS) forms the backbone of internet addressing, translating human-readable domain names into machine-readable IP addresses
• DNS plays a crucial role in Technology and Policy by enabling seamless internet navigation and raising important questions about internet governance and control

Structure of domain names

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• Hierarchical structure consists of labels separated by dots (www.example.com)
• Right-most label represents the top-level domain (TLD)
• Subdomains appear to the left of the main domain name
• Maximum length of 253 characters for a full domain name
• Each label limited to 63 characters

DNS hierarchy

• Root servers sit at the top of the DNS hierarchy
• 13 logical root server clusters distributed globally
• TLD servers manage specific top-level domains (.com, .org, .net)
• Authoritative name servers host information for specific domains
• Recursive resolvers handle queries from client devices

Top-level domains vs subdomains

• Top-level domains (TLDs) include generic TLDs (gTLDs) and country code TLDs (ccTLDs)
• gTLDs serve specific purposes (.com for commercial, .edu for educational institutions)
• ccTLDs represent countries or territories (.uk for United Kingdom, .jp for Japan)
• Subdomains allow for further organization within a domain (blog.example.com, shop.example.com)
• Subdomains can be managed independently of the main domain

DNS resolution process

• DNS resolution translates domain names into IP addresses, enabling internet communication
• This process highlights the decentralized nature of the internet, a key consideration in technology policy discussions

Recursive vs iterative queries

• Recursive queries involve resolvers querying other servers on behalf of the client
• Resolvers handle the entire resolution process, returning the final answer to the client
• Iterative queries require the client to perform multiple queries to different name servers
• Each server in the iterative process responds with the best information it has
• Recursive queries offer convenience for clients but place more load on resolvers

Caching in DNS

• DNS caching stores recently resolved queries to improve performance
• Cached records have a Time to Live (TTL) value determining how long they remain valid
• Positive caching stores successful resolutions
• Negative caching remembers non-existent domain lookups to prevent repeated queries
• Caching occurs at multiple levels (browser, operating system, ISP)

DNS record types

• DNS records contain various types of information about domain names
• Understanding record types helps in managing domain configurations effectively

A and AAAA records

• A (Address) records map domain names to IPv4 addresses
• AAAA (quad-A) records map domain names to IPv6 addresses
• Multiple A or AAAA records can exist for a single domain (load balancing)
• TTL values determine how long these records can be cached

CNAME and MX records

• CNAME (Canonical Name) records create aliases for domain names
• CNAMEs point one domain name to another (blog.example.com to example.com)
• MX (Mail Exchanger) records specify mail servers for a domain
• MX records include priority values to determine the order of mail server usage
• Multiple MX records can provide redundancy for email delivery

TXT and SRV records

• TXT (Text) records store arbitrary text information for a domain
• TXT records often used for domain ownership verification and email security (SPF, DKIM)
• SRV (Service) records define the location of specific services
• SRV records include information on protocol, service name, priority, weight, port, and target
• Commonly used for VoIP, instant messaging, and other network services

DNS security

• DNS security measures protect against various threats and vulnerabilities
• These security enhancements have significant implications for privacy and trust in online communications

DNSSEC implementation

• DNSSEC (Domain Name System Security Extensions) adds cryptographic signatures to DNS records
• Protects against DNS cache poisoning and man-in-the-middle attacks
• Involves a chain of trust from the root zone down to individual domain records
• Requires support from domain registrars, DNS providers, and resolvers
• Challenges include increased complexity and potential for amplification attacks

DNS over HTTPS (DoH)

• Encrypts DNS queries using HTTPS protocol
• Prevents eavesdropping and manipulation of DNS traffic
• Bypasses traditional DNS infrastructure, potentially affecting network-level security controls
• Supported by major browsers (Firefox, Chrome) and operating systems
• Raises concerns about centralization of DNS resolution

DNS over TLS (DoT)

• Encrypts DNS queries using Transport Layer Security (TLS)
• Operates on a dedicated port (853) unlike DoH which uses standard HTTPS port
• Provides similar privacy benefits to DoH but maintains separation of DNS traffic
• Easier to implement at the operating system level
• Less likely to bypass enterprise security controls compared to DoH

Domain name registration

• Domain registration process involves multiple stakeholders and regulatory considerations
• Policies surrounding domain registration impact internet accessibility and intellectual property rights

Registrars and registries

• Registrars act as intermediaries between domain buyers and registries
• ICANN-accredited registrars must follow specific guidelines and policies
• Registries maintain the central database for specific TLDs
• Separation of registrar and registry functions promotes competition
• Thick vs thin registries determine the amount of data stored at the registry level

WHOIS database

• WHOIS provides public access to domain registration information
• Contains registrant contact details, creation and expiration dates
• Privacy concerns led to the development of WHOIS privacy services
• GDPR implementation has significantly impacted WHOIS data availability
• RDAP (Registration Data Access Protocol) designed as a more structured replacement for WHOIS

Domain name disputes

• UDRP (Uniform Domain-Name Dispute-Resolution Policy) handles trademark-related domain disputes
• UDRP provides a streamlined process for resolving cybersquatting cases
• National laws (Anti-Cybersquatting Consumer Protection Act in the US) offer additional protections
• Reverse Domain Name Hijacking refers to bad faith attempts to deprive a registrant of a domain
• Alternative dispute resolution mechanisms exist for specific TLDs

DNS management tools

• DNS management tools facilitate the administration and optimization of domain configurations
• These tools play a crucial role in maintaining the stability and performance of internet services

Zone file configuration

• Zone files contain DNS records for a specific domain
• Include SOA (Start of Authority) record defining zone parameters
• NS records specify authoritative name servers for the zone
• $ORIGIN and$TTL directives set default values for the zone
• Tools like BIND, PowerDNS, and cloud DNS services simplify zone file management

DNS propagation

• DNS propagation refers to the time taken for changes to spread across the DNS hierarchy
• Affected by TTL values of existing records
• Propagation checkers help monitor the status of DNS changes globally
• Strategies for minimizing propagation time include lowering TTL values before changes
• Anycast DNS can help reduce propagation times by routing queries to the nearest server

Load balancing with DNS

• DNS-based load balancing distributes traffic across multiple servers
• Round-robin DNS assigns different IP addresses in rotation
• Weighted round-robin allows for uneven distribution based on server capacity
• Geolocation-based DNS directs users to the nearest server
• Health checks can automatically remove unresponsive servers from the rotation

Policy implications of DNS

• DNS management intersects with various policy areas, including privacy, security, and free speech
• Technology policies must consider the global nature of DNS and its impact on internet governance

Internet governance

• ICANN (Internet Corporation for Assigned Names and Numbers) oversees global DNS coordination
• Multistakeholder model involves governments, private sector, and civil society in decision-making
• Debates over the role of national governments in DNS management
• Transition of IANA functions from US government oversight to global multistakeholder community
• Regional Internet Registries (RIRs) manage IP address allocation within their regions

Censorship and content control

• DNS can be used as a tool for internet censorship through domain blocking
• DNS poisoning redirects users to incorrect or malicious websites
• Circumvention techniques include alternative DNS servers and encrypted DNS protocols
• Content delivery networks (CDNs) can complicate censorship efforts
• Balancing free speech with legal and ethical content control remains a challenge

Cybersquatting and trademark issues

• Cybersquatting involves registering domain names to profit from others' trademarks
• Typosquatting targets common misspellings of popular domain names
• Trademark holders can use UDRP or legal action to recover infringing domains
• Sunrise periods give trademark holders priority registration for new TLDs
• Trademark Clearinghouse provides centralized validation of trademark rights

Future of DNS

• The evolution of DNS will have significant implications for internet architecture and policy
• Emerging technologies and naming systems may challenge the traditional DNS model

New gTLDs

• ICANN's new gTLD program dramatically expanded the number of top-level domains
• Brand TLDs allow companies to operate their own namespace (.google, .amazon)
• Geographic TLDs represent cities and regions (.nyc, .london)
• Internationalized Domain Names (IDNs) support non-ASCII characters in domain names
• Challenges include trademark protection and potential user confusion

Decentralized naming systems

• Blockchain-based naming systems aim to create censorship-resistant domains
• Handshake proposes a decentralized root zone managed through proof-of-work
• Ethereum Name Service (ENS) provides human-readable names for cryptocurrency addresses
• Challenges include integration with existing DNS infrastructure
• Potential for increased privacy but also complications in law enforcement and dispute resolution

DNS and IoT devices

• Growth of IoT devices increases demand for DNS resources
• Multicast DNS (mDNS) enables local name resolution without central servers
• DNS-SD (Service Discovery) allows devices to advertise their capabilities
• Security concerns arise from potentially vulnerable IoT devices participating in DNS
• Need for scalable and secure DNS solutions to support billions of connected devices