tailieunhanh - Tìm hiểu về DNS

Cơ sở dữ liệu(CSDL) của DNS là một cây đảo ngược. Mỗi nút trên cây cũng lại là gốc của 1 cây con. Mỗi cây con là 1 phân vùng con trong toàn bộ CSDL DNS gọi là 1 miền (domain). Mỗi domain có thể phân chia thành các phân vùng con nhỏ hơn gọi là các miền con (subdomain). Mỗi domain có 1 tên (domain name). Tên domain chỉ ra vị trí của nó trong CSDL DNS. Trong DNS tên miền là chuỗi tuần tự các tên nhãn tại nút đó đi ngược lên nút gốc của cây và phân cách. | Address Conversion Functions and The Domain Name System Refs: Chapter 9 RFC 1034 RFC 1035 Netprog: DNS and name lookups Hostnames IP Addresses are great for computers IP address includes information used for routing. IP addresses are tough for humans to remember. IP addresses are impossible to guess. ever guessed at the name of a WWW site? Netprog: DNS and name lookups The Domain Name System The domain name system is usually used to translate a host name into an IP address . Domain names comprise a hierarchy so that names are unique, yet easy to remember. Netprog: DNS and name lookups DNS Hierarchy edu com org jp rpi albany Netprog: DNS and name lookups Host name structure Each host name is made up of a sequence of labels separated by periods. Each label can be up to 63 characters The total name can be at most 255 characters. Examples: Netprog: DNS and name lookups Domain Name The domain name for a host is | Address Conversion Functions and The Domain Name System Refs: Chapter 9 RFC 1034 RFC 1035 Netprog: DNS and name lookups Hostnames IP Addresses are great for computers IP address includes information used for routing. IP addresses are tough for humans to remember. IP addresses are impossible to guess. ever guessed at the name of a WWW site? Netprog: DNS and name lookups The Domain Name System The domain name system is usually used to translate a host name into an IP address . Domain names comprise a hierarchy so that names are unique, yet easy to remember. Netprog: DNS and name lookups DNS Hierarchy edu com org jp rpi albany Netprog: DNS and name lookups Host name structure Each host name is made up of a sequence of labels separated by periods. Each label can be up to 63 characters The total name can be at most 255 characters. Examples: Netprog: DNS and name lookups Domain Name The domain name for a host is the sequence of labels that lead from the host (leaf node in the naming tree) to the top of the worldwide naming tree. A domain is a subtree of the worldwide naming tree. Netprog: DNS and name lookups Top level domains edu, gov, com, net, org, mil, Countries each have a top level domain (2 letter domain name). New top level domains include: .aero .biz .coop .info .name .pro Netprog: DNS and name lookups DNS Organization Distributed Database The organization that owns a domain name is responsible for running a DNS server that can provide the mapping between hostnames within the domain to IP addresses. So - some machine run by RPI is responsible for everything within the domain. Netprog: DNS and name lookups DNS DB DNS DB DNS Distributed Database There is one primary server for a domain, and typically a number of secondary servers containing replicated databases. DNS DB Authoritative DNS DB Replicas DNS server Netprog: .