Network Services

Question 1

Examples of Network Services

Answer 1

DHCP, DNS, NAT, EMAIL, HTTP, FILE SERVICES

Question 2

DHCP - two types of addressing

Answer 2

Dynamic and Static:

Question 3

DNS - what is the function

Answer 3

resolve names to IP addresses

Question 4

Explain the DNS lookup process

Answer 4

To resolve a name, the resolver will check its own DNS cache. Query then issued to DNS server. If the answer is not found, the DNS server will query higher-level DNS servers that are called recursive queries. There are higher level DNS servers, they will only be forwarded to these servers if they cannot resolve recursive queries.

Question 5

What are the steps for DNS lookup process.

Answer 5

step 1. User types in FQDN into a browser.
step 2: A DNS query is sent to the client’s listed DNS server.
step 3: DNS server searches for match of FQDN to IP
step 4:DNS query response sent back to the client with the UP address for the FQDN.
step 5: DNS server matched FQDN with IP.

Question 6

Describe DNS message format

Answer 6

DNS uses port UDP port 53. If a DNS response exceeds 512 bytes, Dynamic DNS is used (DDNS). DNS uses the same message format for client queries, error messages, server messages, etc.

Question 7

What are the sections of the DNS message format?

Answer 7

1. Question - question for the server, contains the domain name to be resolved, query type and class domain.
2. Answer: DNS resource record for the query.
3. Authority: Contains the RRs for the domain authority.
4. Additional: relevant to query responses only.

Question 8

What is Dynamic DNS?