Addressing and Naming

Question 1

What are some advantages of using structured models?

Answer 1

makes it easier to:
- read network maps
- operate network management software
- meet goals for usability
- design filters on firewalls and routers
- implement route summarisation

Question 2

Describe what DNS is.

Answer 2

Domain Name System maps names to IP addresses and supports hierarchical naming. A DNS server has a database of resource records (RRs) that maps names to addresses in the servers “zone of authority”. Client queries server uses UDP port 53 for name queries and replies, and uses TCP port 53 for zone transfers.

DNS is a client/server model. The Client is configured with the IP address of a DNS server (either manually or a DHCP can provide the address). The DNS resolver software on the client machine sends a query to the DNS server. The Client may ask for recursive lookup:
A DNS server may offer recursion which allows the server to ask other servers. When a DNS server receives a response from another server, it replies to the resolver client software. The server also caches the info for future requests.

Question 3

What are some advantages of DNS?

Answer 3

DNS has user-friendly navigation: it allows users to access easy-to-remember domain names instead of complex IP addresses e.g “google.com” instead of. 8.8.8.8.
DNS is scalable: DNS is highly scalable and its hierarchical structure, divided into multiple levels (root, TLD, authoritative servers) enables efficient distribution and management of queries across the internet.

Question 4

What are some disadvantages of DNS?

Answer 4

Security Vulnerabilities: DNS is susceptible to various security threats including DNS spoofing/cache poisoning, DDoS attacks and Domain hijacking.
Latency Issues: although DNS caching speeds up response times, if a DNS resolver must query multiple servers to resolve a domain, it can introduce latency (time delay), network issues or slow DNS servers can further exacerbate this problem.