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BBF221 FINAL CA - FT
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- [3 marks] Assuming the same context as for b) above, what resource records will you be placing in the company’s DNS server [4 marks]
- [2 marks] Find the number of addresses in each subnet [2 marks] Find the first and last allocatable addresses in subnet 1. [2 marks]
| QUESTION FOUR
A DNS resolver typically issues a query using UDP but may also use TCP. Is there a problem using TCP for this purpose? If so, what do you suggest is the solution? [3 marks] Assume you are setting up a company network that has the following servers: DNS server: “dns1.compxyz.com” (IP: “128.118.13.50”) Web server: “compxyz.com” with two IP addresses as “128.118.12.56” and “128.118.12.58”. The web server also bears the name “www.compxyz.com”. Email server: “email.compxyz.com” (IP: “128.119.12.60”, company email address: “username@compxyz.com”). What resource records (RRs) will you be providing to the .com authoritative registrar? [3 marks] Assuming the same context as for b) above, what resource records will you be placing in the company’s DNS server? [4 marks] The Internet Group Management Protocol (IGMP) is a communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships. Explain how IGMP functions to achieve its objectives. [2 marks] An organization is granted the block 211.17.180.0/24. The administrator wants to create 32 subnets: Find the subnet mask required [2 marks] Find the number of addresses in each subnet [2 marks] Find the first and last allocatable addresses in subnet 1. [2 marks] Find the first and last allocatable addresses in subnet 32 [2 marks] ANSWER DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests.DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server. The Transmission Control Protocol (TCP) isused when the response data size exceeds 512 bytes, or for tasks such as zone transfers. Some resolver implementations use TCP for all queries.IP Fragmentation and TCP SegmentationThe presence of larger IP packets, such as those found when using DNS (mainly due to zone transfers, EDNS, and DNSSEC), translates to an increase in the probability that a large packet containing DNS information will exceed the Maximum Transmission Unit (MTU) at some point in transit. In cases where the packet exceeds the configured MTU of a Layer 3 interface, the packet will require fragmentation. However, in certain cases, the packet configuration (for example, if the Don't Fragment (DF) bit is set (= 1)), or the network configuration (for example, ICMP messages indicating packets need to be fragmented are not received by the originating host) may not allow transmission of a fragmented packet. (compxyz.com, dns1.compxyz.com, NS)(dns1.compxyz.com, 128.118.13.50, A) (compxyz.com, 128.118.12.56, A)(compxyz.com, 128.118.12.58, A)(www.compxyz.com, compxyz.com, CNAME)(email.compxyz.com, 128.119.12.60, A)(compxyz.com, email.starwar.com, MX) A multicast router connected to a network has a list of multicast addresses of the groups with at least one loyal member in that network. For each group, there is one router that has the duty of distributing the multicast packets destined for that group. Find the subnet mask. 24+5 =29 , /29 b. Find the number of addresses in each subnet. 2^(32-29) = 2^3=8 c. Find the first and the last address in the first subnet. First Address : 211.17.180.0 Mask :0.0.0.7 Last Address : 211.17.180.7 Find the first and the last address in the last subnet (subnet 32). 8 * 31 = 247 First Address in subnet1 : 211.17.180.0 number of addresses : 0.0.0.247 First Address in subnet32: 211.17.180.247 First Address in subnet32: 211.17.180.247 number of addresses : 0.0.0.7 First Address in subnet32: 211.17.180.255 Download 290.5 Kb. Share with your friends:
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