Intrvw: Difference between revisions
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Explain SIP Flow
Does it uses TCP? (no it uses UDP for both SIP & RTP)
= Citrix (Anshu) =
Reno
Difference b/w Http/1.0 and Http/1.1 - Only Persistent connections & more methods? yes methods as well
Cookies, Caching and proxy - not in much detail types and little explanation is fine
Time Stamping : [http://stackoverflow.com/questions/7880383/what-benefit-is-conferred-by-tcp-timestamp]
RTT calculate = Time to segment send + ack received without retransmission
How MSS value is decided = decided by server & client & sent in 1st & 2nd Packet? send informs its MSS ,exchanged in 1st and 2nd packets of 3 way handshake
Relationship between MSS and MTU = MTU - [IP & TCP Headers] = MSS
Difference b/w them IPSec and SSL? [https://eprint.iacr.org/2004/314.pdf]
Why IPSec uses two phases and ssl one phase? main purpose of 2nd phse of IPSEC is to provide PFS as it is normally used for long duration connections (eg VPN ) while SSL is used for comapartively short durations additinal steps are required to enable PFS in SSL,Refer link[http://www.slashroot.in/what-perfect-forward-secrecy-and-its-impact-ssl-https]
Nat-t hash calc = RFC file's HASH? Yes - [https://www.ietf.org/rfc/rfc3947.txt]
The HASH is calculated as follows:
HASH = HASH(CKY-I | CKY-R | IP | Port)
Nat which side, marker?
How query resolved? Meaning Recursive & Iterative? clients send recursive queries, ISP DNS servers do iterative queries likewise flow can be explained
Reverse DNS query? Where is this used? in IPv6? mails, nslookup etc.
DHCP Flags - Which Flags? all are important - DHCPOFFER: 0x8000 for broadcast, 0x0000 for unicast
DHCP - DORA Process, Flags, Relay
Http status code
Http headers
Cookies, Caching and proxy
Types of ARP and explanation & usage
TCP and UDP difference
3 Way Hand shake
TCP flags
Difference b/w PSH and URG
TCP options
MSS, SACK,
Widow scaling
Slow start and fast re-transmission
TCP well known ports
Fragmentation
SSL Handshake
DNS Types of records, Zones, How query resolved, Reverse DNS query
HTTP Topics:
<pre>
7 Header Fields
7.1 General Headers
7.1.1 Cache-Control
7.1.1.1 Request
7.1.1.2 Response
7.1.2 Connection
7.1.6 Transfer-Encoding
7.1.7 Upgrade
7.1.8 Via
7.2 Client Request Headers
7.2.6 Cookie
7.2.10 If-Match
7.2.11 If-Modified-Since
7.2.12 If-None-Match
7.2.13 If-Range
7.2.14 If-Unmodified-Since
7.2.18 Referer
7.2.19 TE
7.3 Server Response Headers
7.3.3 ETag
7.3.5 Proxy-Authenticate
7.3.8 Set-Cookie
7.4 Entity Headers
7.4.10 Last-Modified
8 Caching (overview is fine if not able to read completely )
8.1 Request Directives
8.2 Response Directives
10 Security
10.3 DNS Spoofing
10.6 Proxies and Caching
</pre>
Http status code
Http headers
Cookies, Caching and proxy
Types of ARP and explanation & usage
TCP and UDP difference
3 Way Hand shake
TCP flags
Difference b/w PSH and URG
TCP options
MSS, SACK,
Widow scaling
Slow start and fast re-transmission
TCP well known ports
Fragmentation
SSL Handshake
DNS Types of records, Zones, How query resolved, Reverse DNS query
DHCP - DORA Process, Flags, Relay
= Citrix =
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