DOMAIN NAME SYSTEM (DNS)

Domain Name System (DNS)

Domain Name System (DNS)

Introduction

Domain Name Systems (DNS - Domain Name Systems) are a form of distributed databases that are used by TCP/IP, for the purpose of mapping host names with the IP addresses. DNS is also used to route e-mail. We use the term distributed because the Internet on a single node does not store the entire required information (Cricket & Paul, 2006: 3). A database of information is maintained by every node (company, department, campus or university). A server, which can send a request over the Internet to other systems, is also a part of DNS.

From an application perspective, access to the DNS carried out by resolver (resolver) (parser (resolver) - routines that are used for creating, sending and interpreting packets used name server Internet). On UNIX systems, the parser can be accessed through two library functions get host byname (3) and get host by address (3), which are linked with the application when it is built. The first takes it as an argument and provides the IP address if the hostname is entered, and the second takes as its argument and returns the IP address of the host name. Parser is contacting one or more servers, DNS (name servers), to establish this correspondence.

Question 1: How would you describe the size of the Domain Name System?

Port 53 and UDP is basically used by a typical DNS and the maximum packet size of 512 bytes is used. The standard provides that TCP port 53 returns the application if a response exceeds the maximum size. This is a rare case because firewalls often tend to block TCP port 53 (Brain, 2000: website). The same TCP port number makes the zone transfers are and for the purpose of security, servers restrict transfer areas.

The extension EDNS 0 (two thousand six hundred and seventy-one RFC) allows using a higher packet size, IPv6 as for DNSSEC recommends it management for the same. The standard requires an associated class requests. CH (Chaos), Class IN (Internet) and HS (Hesiod (in)) are defined, however, only the IN class is in practice. BIND uses the chaos class in order to reveal the version number.

Question 2: Which 3 components are the most important for DNS operations and how are they related to each other

For the practical operation of the DNS system uses three main components (Douglas & Mark, et al, 1984: 23):

DNS Clients: A DNS client program running on the user's computer that generates DNS resolution requests to a DNS server names.

DNS Servers: To answer the requests of customers. Recursive servers have the ability to forward the request to another server if you do not have the requested address.

And areas of authority, portions of the domain name spaces that store the data. Each area of ??authority includes at least one domain and possibly its sub-domains, if the latter are not delegated to other areas of authority.

Operational Considerations

Updating the DNS

Updates are made ??on the primary server in the domain, the secondary servers copying information from the primary server ...