1. Describe the terms below:
Name is a string of bits or characters that is used to refer to an entity. Entity in Distributed System can be practically anything. It also an associations between some elements in a set of names and some elements in a set of values
Address refers to access point and entity. An entity can provide more than one access point; usually access point will host running a specific server with combination an IP address and port number. An entity may change its access point and address when computer moves to another location.
c. Name Space
Name space used to define a structure names to use a naming graph which is a directed acyclic graph. Each nodes of the naming graph correspond to the entities of the system. There are a number of root nodes of in degree zero, and leaf nodes of out degree zero. Non-leaf nodes are called directory nodes. Nodes are labeled with node identifiers. The directed arcs of a naming graph are labeled with arc names. Examples of h naming systems are the Internet Domain Name System.
d. Address Resolution
An address resolution is any means of overcoming the differences between two different address systems on a network. Address Resolution Protocol (ARP) is to exchanges between network interfaces connected to an Ethernet media segment. At the same time, to map an IP address to a link layer address on demand. Link layer addresses are hardware addresses on Ethernet cards and IP addresses are logical addresses assigned to machines attached to the Ethernet. When Internet Layer was identifier, ARP as a computer networking protocol will determine a network host's link layer or hardware address.
2. Explain the basic operation of DNS
DNS primarily used for looking up host addresses and mail servers into its IP address. Every host is affected an IP address that must known the host to communicate. DNS will translate from a name like "eff.org" into a raw number called an IP address then; all internet traffic requires these numbers to work. DNS provides a way to know the IP address of any host on the Internet. DNS can do directly, but most personal computers will ask another computer at ISP or corporation to do the work. The person who are responsibility to run it will installed the list and the list will came with the DNS software, because everybody in the world uses a similar list. The master will resolved the any name want to ask about. The list known as the root server of DNS, a score of this root server around world and they will copy their own data from one master server. Each one has the same data inside. Usually, the root servers don't actually contain much. They only make a list where they will find the servers that can look up names in the "top level domains" like .com, .org, .us, .uk and etc. Once the root server tells your system where the master ".org" server is, your system asks it where "eff.org" is. In other words, it gets back the raw internet IP address, the low level "phone number" of the internet. Finally, your computer can talk directly to the computers at eff.org.
3. Discuss how DNS achieves scalability, reliability, and speed. Discuss the issues and problems in regard to scalability, reliability, speed and security that remained to be solved in DNS
The scalability achieve when system remains effective when there is a significant increase in the number of resources and the number of users. The DNS achieve that by working well in replication and caching which DNS scaled from small numbers to millions. DNS replication use to replicate the DNS IP address and computer name stored in Active Directory to all local domain controllers but it is not replicated to domain controllers outside the domain. The issues related with hierarchical location services which root node are required tom store a location record for each entity and it process. The problem is without any special measure, the root may be required handle so many update request and process and that will become a bottleneck. So, each partition roof node or directly node into subnodes. Each subnodes responsibility to handling request related with specific subset of entities which it supported by the location services.
The issues related with reliability are Service Level Agreements where a lot of the DNS provider's out there offer a 100% SLA or near to it. It is all about how good they can provide service and reliable of network they have but will they be responsible for something happened. So, each organizer needs to study and investigate each company about their history of providing the DNS. Organizer need to know how important 1 minute's means to their company if something happened to their DNS.
The DNS server achieve the speed when it able to resolve the website or domain name that typed in browser faster where the browsing speed is automatically increases to the maximum speed. The issues related with the peer queries are sent only after trying to obtain a fast response from the DNS. It will look up are generally fast, and then avoid from unnecessary traffic also to avoid from overloading marginal DNS servers. The CoDNS will apply if the DNS is too slow then the peer will try to resolve the query before the local DNS minimal overhead if the system is function properly. Even using the minimal overhead only 1 extra lookup the average response time reduces by more than half and no overhead if the lookup is local (98% of the requests).
The issues regard to security a target for hackers. DNS are location at everywhere and an expert hacker can take over a server or simply use DNS implementation to making reorientation traffic. There are two ways DNS can be hacked: by using protocol attacks (attacks based on how DNS is actually working) or by using server attacks (attacks based on the bugs or flaws of the programs or machines running DNS services). DNS need to more secure to avoidance so their information not be hack or corruption.