Explaining Network Services Flashcards
1
Q
DCHP
A
Dynamic Host Configuration Protocol
- Automatic allocation of an IP adress, subnet mask and additional parameters, like default gateway or DNS server
- Host is configured to user DHCP by specifying in TCP/IP configuration that it shoud automatically obtain IP
2
Q
DHCP Server
A
- Normally deployed as service of network opreating system or through appliance such as a switch or router
- Must be allocated a static IP address and configured with a pool of IPs and a subnet masks
3
Q
Scope
A
- Range of addresses and options configured to a single subnet
- Must provide start and end IP address and subnet mask
- No scope can cover more than one subnet or vice versa
4
Q
DHCP Lease Time
A
- Client can renew lease when at least half of the time has elapses (T1 Timer).
- If DHCP server does not respond, client attempts to rebind same lease configuration with any DHCP server, by default at 87.5% of lease time up (T2 timer)
- Long lease time mean less need to renew
- Short least time means IP pool is refilled more ofte.
5
Q
DHCP Options
A
- Other IP related settings offers in DHCP configuraitons
- Each is identified with tag byte or decimal value between 0-255
- ExampleSS:
Default gateway
IP address of DNS server
DNS suffixx
Useful server options like NTP, TFTP or VoIP proxy
6
Q
DCHP Reservations
A
- Mapping of MAC address to specific IP address withing DHCP server address pool
- When server receives request from given interface, it always gives same IP address
- Automatically allocated reserveration refers to address that is permanently leased to a client
- Distinct from Static allocation as the administrator does not determine which specific IP address will be leased
7
Q
DHCP Relay
A
- Configuration to provide forwarding of DHCP traffic between subnets
- Routers that can do it are RFC 1542 Compliant
- Intercepts DHCP broadcast frames and applies appropriate unicast address for DHCP server
- Reduces the need for multiple DCHP servers for each subnet
8
Q
IP Helper
A
- Configuration on router to allow set types of brodcast traffic to be forwarded to an interface.
- Supports function of DHCP Relay
9
Q
SLAAC
A
Stateless Address Autoconfiguration
- IPv6 process that locates routers and generates host address with suitable network prefixx automatically.
- DCHPv6 is often just used for option settings rather than leases for host addresses.
10
Q
Host name
A
- Assigned to computer by administrator
- Must be unique on local network
11
Q
FQDN
A
Fully qualified domain name
- Used to provide unique indentity for a host belonging to particular network
- Made up of host name and domain suffix
- Domain name must be registered with registrar to ensure it is unique
- Must follow certain rules:
1. host name must be unique within domain
2. Total length cannot exceed 253 characters, with each label(part of name defined by a period) not exceeding 63
3. Use letter, digit and hyphen characters only.
4. not case sensitive
12
Q
Iterative Lookups
A
- Name server responds to query with either requested record or address of name server at a lower level that is authoritative for the namespace
- Makes no effort to make queries for information it does not have.
13
Q
DNS
A
Domain Name System
- Global hierarchy of distributed names server databases that contain information on domains and hosts withing domains.
- At top is the root, which just contains .
- Next is top level domains(.com,.org,.uk., .gov, etc.)
-
14
Q
Recursive lookup
A
- if queried server is not authoritative, it does take on take of querying other name servers until it finds requested record or times out.
- Name servers listed in clients TCP/IP configuration accept recursive queries
15
Q
Resource Records
A
- Record in DNS zone that allows a name server to resolve queries for names and services hosted into IP addresses.
- Can be updated manually (statistically) or can be generated dynamically
16
Q
SOA
A
State of Authority record
- identifies authoritative name server that maintains complete resource records for the zone
- Also contains contact information for the zone and serial number for version control
17
Q
NS records
A
Name Server Records
- identify authoritative DNS Name servers for the zone
- Most zones are configured with secondary name servers for redundancy and load balancing
18
Q
A record
A
Address Record
- Used to resolve a host name to an IPv4 address
19
Q
CNAME Record
A
Canonical Name Record (or alias)
- Used to configure alias for an existing A record
- Also used to make DNS Administration easier
20
Q
MX Record
A
Mail Exchange Record
- used to identify email server for the domain
- Host identified must have associated A or AAAA record
- Cannot point to CNAME
21
Q
SRV Records
A
- Resolves to service name and port on which an application is hosted
- Often used for VoIP and media servers
- Essential part of Active Directory
22
Q
TXT Record
A
- Used to store any free form text that may be needed to support other network services
- Used as part of SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail)
23
Q
SPF Record
A
Sender Policy Framework Record
- Used to list the IP addresses or names of servers that are permitted to send from a particular domain
24
Q
DKIM Record
A
Domain Keys Identified Mail
- Used to decide whether you should allow received mail form given source
- can used encrypted signatures to prove that message originated from where it claims
25
Q
PRT Record
A
Pointer Record
- Reverse DNS lookup zone
- Uses a special domain named by the first 3 octets of IP Addresses in the zone in reverse order appended with in-addr.arpa.
26
Q
DHCP Discover
A
- Type of packet sent by DHCP client a DHCP server
- Sent over UDP with server listening on port 67 and client on port 68
27
Q
DCHPOFFER
A
- Packet sent by DHCP server as response to DHCPDISCOVER
- Contains IP address and configuration information
28
Q
DCHPREQUEST
A
- Type of packet sent by client to DHCP server to accept DHCPOFFER
29
Q
DHCPACK Packet
A
- Packet sent by server to client accepting DHCP
30
Q
DORA
A
Discover, Offer, Request and Ack(nowlege)
- DHCP Lease process
31
Q
T1 Timer
A
- Half the time of DHCP Lease
- When a client can renew the lease
32
Q
T2 Timer
A
- When a client will attemp to rebind same lease configuration with any DHCP server
- Happens at 87.5=% of lease time
33
Q
DNS Root
A
- Top of DNS hieararchy
- Defined by .
- 13 root levels, A-M
34
Q
DNS TLD
A
Top-level domain
- Immediately below root in DNS hierarchy
- Most prevalent are generic like .com, .org, .net, or .gove or .uk
- Managed by ICANN and country-specific orgs
35
Q
DNS Information Process
A
- Trace records down from root through hierarchy
- Root servers have complete information about TLD servers
- TLD has information related to second-level domains
- No name server has complete information for all domains
