Understanding Domain Name System (DNS) Hierarchy and Structure
Explore the hierarchical structure of the Domain Name System (DNS) through detailed explanations and visual representations. Learn about top-level domains, fully qualified domain names, namespace organization, and resource records. Enhance your understanding of how DNS translates domain names to IP addresses and maintains the global domain name hierarchy.
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DNS & BIND SPARCS 12 coffee
ara.kaist.ac.kr 143.248.234.103
ara.kaist.ac.kr DNS 143.248.234.103
DNS Domain Name System Hierarchical distributed naming system Translate b/t two principal namespaces domain name hierarchy Internet Protocol(IP) address Maintains the domain name hierarchy 192.0.43.10 (IPv4) 2620:0:2d0:200::10 (IPv6) IP address www.example.com domain name hierarchy
Domain Name Space Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go kaist Sub domains( ) ara otl moodle
Domain Name Space Root Top Level Domain com org net kr us jp DNS is maintained by a Second Level Domain distributed database system google naver co ac go kaist Sub domains( ) ara otl moodle
Domain Name Space Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go kaist Sub domains( ) ara otl moodle Each node or leaf in the tree has zero or more resource records.
Domain Name Space Sub domain Top level http://www.example.co.kr/ Sub domain Second level Label : letter(a-z or A-Z), digits(0-9), hyphen(-), cannot use hyphen in first letter Each label may contain up to 63 characters. The full domain name may not exceed a total length of 253 characters in its external dotted-label specification. Domain name consists of one or more labels Each label is delimited by dots This tree of subdivisions may have up to 127 levels.
TLD(Top Level Domain) (generic domain, gTLD) com, net, org, info, (country code domain, ccTLD) kr, us, eu, jp, (infrastructure domain)
FQDN(Fully Qualified Domain Name) . root domain null label ( . ) ara.kaist.ac.kr (x) ara.kaist.ac.kr. (o)
PQDN(Partially Qualified Domain Name) Label doesn t end with null string. kaist.ac.kr www.example.co.kr www.example.co.kr.kaist.ac.kr . Resolver www.example.co.kr.(FQDN) name server -> www.example.co.kr.kaist.ac.kr
DNS zone Portion of a domain name space. kaist.ac.kr zone aaaaaaaaa ara.kaist.ac.kr kaist.ac.kr otl.kaist.ac.kr ac.kr zone s moodle.kaist.ac.kr ac.kr postech.ac.kr zone aaaaaa www.postech.ac.kr postech.ac.kr library.postech.ac.kr
Resource Records(RR) Name Domain name as key index TTL Time to Live on cache table Class only IN(internet) Type A-1, NS-2, SOA-6, etc. RDATA Raw data, depends on the type
Resource Records - Types Type A AAAA NS CNAME SOA MX Code 1 28 2 5 6 15 A host address 32bit IPv4 IP6 address 128bit IPv6 An authoritative name server The canonical name for an alias Alias Marks the start of a zone of authority Zone Mail exchange http://en.wikipedia.org/wiki/List_of_DNS_record_types
DNS protocol Section Header Question Answer Authority Additional Value Metadata The question for the name server RRs answering the question RRs pointing toward an authority RRs holding additional information
Querying Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go google.com? kaist Sub domains( ) ara otl moodle
Querying Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go google.com? kaist Sub domains( ) ara otl moodle
Querying Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go google.com? kaist Sub domains( ) ara otl moodle
Querying Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go google.com? kaist Sub domains( ) ara otl moodle
Update Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go new resource record (sparcs.kaist.ac.kr) kaist Sub domains( ) ara otl moodle
Update Root Top Level Domain com org net kr us jp Second Level Domain google naver co ac go kaist Sub domains( ) ara otl moodle sparcs
! sudo apt-get install dnsutils
Hosts? windows/system32/drivers/etc/hosts /etc/resolv.conf in Linux
dig(domain information grouper) dig [@global-server] [domain] [q-type] {q-opt} Ex) dig @ns.kaist.ac.kr otl.kaist.ac.kr A
BIND? Berkeley Internet Name Domain DNS 1980 UC Berkeley 4
BIND BIND 4 by the Computer Systems Research Group(CSRG) at UC Berkeley. BIND 8 by the Internet Systems Consortium(ISC) BIND 9 was released in September 2000
master & slave? DNS slave master zone master , slave
RDATA of SOA mname zone primary master name server domain name rname zone serial zone (YYYYMMDDNN) refresh, retry, expire , , minimum dafault TTL
NS, A @ IN NS ns.mazic.org. coffee IN A 134.248.234.103
! DNS ! ( ID).wseminar#.sparcs.org
Reference SPARCS seminar hodduc - 20100705 SPARCS seminar boolgom 20110629 SPARCS seminar gangok 20110701 http://en.wikipedia.org/wiki/Domain_Nam e_System http://dns.kisa.or.kr/kor/main.jsp DNS .pdf
Reference http://blog.naver.com/une4535?Redirect= Log&logNo=140055620130 http://www.freesoft.org/CIE/Topics/77.htm
