THE DNS (DOMAIN NAME SYSTEM)

Before the DNS, all computers connected to the internet through ARPANET (the worlds first operational packet switching network). They were connected through a single file (HOSTS.TXT), this provided mapping between host names and network addresses. However, relying on one file for the whole internet is risky business, and a new system was needed. That’s where the DNS comes in… HOW IT STARTED

Think of the DNS as a phonebook, because that’s essentially what it does. Instead of having to memorise a set of numbers for a website, you just type in the domain name and you’re put through to that site. Imagine having to remember a number like just to log on to your facebook, but thanks to the DNS, you don’t need to. HOW IT WORKS

The DNS has 3 main components: Name Space Name Server Resolver WHAT MAKES THE DNS

The Name Space gives each website a structure. Inside the name space are nodes, these are separated by a period in each address. Every address has to be unique in its own way otherwise collisions and errors may occur. For example, is broken down into two name spaces – facebook and.com, with.com being the TLD (Top Level Domain) THE NAME SPACE

Name servers hold information about name spaces (this includes sub-sections and zones) and the hierarchical tree structure of the DNS, it responds to queries by outlining how domain addresses are translated. There are two types of name servers: Authoritative Name Server Recursive and Caching Name Server THE NAME SERVERS

This provides the results whenever a DNS query is made. There are two types of Authoritative name servers – a master server and a slave server. The master server stores the original copies of all zone records and does the query lookups for each query. The slave server is an exact copy of the master server and is used to share the load with the master. It can also serve as a back up to the master. (What is Authoritative Name Server? 2011) AUTHORITATIVE NAME SERVER

The recursive and caching name server takes a significant amount of load off the authoritative server by acting like an archive. It stores DNS lookup queries so the authoritative name server doesn’t have to answer the query itself, this means it can answer some queries much faster than the authoritative server and also allows the it to answer other queries. (What is Authoritative Name Server? 2011) RECURSIVE AND CACHING NAME SERVER

The resolver's task is to translate any user’s query from a domain name to an IP address and back again. This is done so the user sends and receives the correct domain name and IP address. When a host is configured, it is assigned one default Name Server and IP address. The first place the resolver looks is the name server it is assigned, if it cant find the answer there it asks the root server, which directs it to a name server with the right data. THE RESOLVER

Its almost impossible to specify a size for the DNS. You can look at it in a number of ways. You can look at the ’13’ root servers (not really, there are many hundreds of root servers at over 130 physical locations (Davies, 2007)) Or you can look at the data size, which is ever increasing or the number of domains that are registered. However, no matter which way you look at it, you cant really give it a size…so just accept the fact that it is really, really big. HOW BIG IS THE DNS?

There isn’t really any legislation on the actual DNS itself, but there are laws regarding website domains. Most legal issues concerning the DNS are between two parties (usually a registered company versus an individual) fighting it out for a certain domain name. Here are a few types of cases that have come up: Cyber squatters: Some people bought certain domain names expecting to sell it to companies for a large profit. These people lost as they were violating trademark laws. Competitors: Some companies registered domain names as their own so they can embarrass their competitors. Free riders: Others registered domain names of companies more famous than them so that they can gain from it. DNS LEGISLATION

Like almost every network service, the DNS is susceptible to security risks. Here’s a list for the most dangerous risks facing the DNS: Typosquatting DDoS DNS Amplification Attacks Registrar Hacking Cache poisoning. DNS PROBLEMS

This is when a user registers a domain name that is similar to a registered trademark. Typosquatting can be used to steal information. Researchers from Godai Group say that the obtained 120,000 just by simply typosquatting. They basically registered a domain name similar to one that already existed, and if users made a mistake (by missing a dot) their was sent to the group. They discovered that passwords, sales info and other secrets could be stolen. (Mohan, 2011) TYPOSQUATTING

Distributed Denial of Service attacks. No matter how well protected a website may be, if it can not handle a large number of incoming requests, the sites performance will be degraded or even disabled. (Mohan, 2011) DDOS

By hoodwinking the source address on DNS queries to match that of the intended victim, attackers found that every counterfeit packet sent from one of their bots could be amplified if sent to a recursive name server. The response sent to the victim would be many dozens of times larger than the original query DNS AMPLIFICATION ATTACKS

Most domain names are registered via a registrar company; this epitomizes a single point of failure. If a hacker can hack your account with your registrar they can then control your domain name thus pointing it to any name/web/ server they desire. They can even transfer ownership of the domain to another registrar. (Mohan, 2011) REGISTRAR HACKING

Attackers can insert wrong addressing information into caches. This allows them to send the user to a server that they control, and if the replica site is good enough, the user cannot tell if it is the real thing or not. As it was demonstrated by the “Kaminsky Bug” back in 2008, if an attacker can imitate a site or , they can gain many things like money, secrets, passwords etc. (Mohan, 2011) CACHE POISONING

Alvin. (2006). DNS COMPONENTS. Available: Last accessed 8/01/ What is Authoritative Name Server? (2011). Davies, K. There are not 13 root servers Retrieved from: Ram Mohan. (2011). Five DNS Threats You Should Protect Against.Available: Last accessed 08/01/ Bug picture - Phonebook picture - Name space picure - Typosquatting picture typosquatting-yearlyhttp://techpatio.com/2010/blogging/marketing/google-earn typosquatting-yearly REFRENCES